docs: Update git URLs to the new server

[hans]

Summary

These days, I get redirect warnings during git pulls:

warning: redirecting to https://git.llvm.org/git/llvm.git/

Should we update the docs to point to the new server? There are some references in the Clang docs as well; I'll update those too if this looks good.

docs/GettingStarted.rst

 Git mirrors are available for a number of LLVM subprojects. These mirrors sync
 automatically with each Subversion commit and contain all necessary git-svn
 marks (so, you can recreate git-svn metadata locally). Note that right now
 mirrors reflect only ``trunk`` for each project. You can do the read-only Git
 clone of LLVM via:
 
 .. code-block:: console
 
-  % git clone http://llvm.org/git/llvm.git
+  % git clone https://git.llvm.org/git/llvm.git
 
 If you want to check out clang too, run:
 
 .. code-block:: console
 
   % cd llvm/tools
-  % git clone http://llvm.org/git/clang.git
+  % git clone https://git.llvm.org/git/clang.git
 
 If you want to check out compiler-rt (required to build the sanitizers), run:
 
 .. code-block:: console
 
   % cd llvm/projects
-  % git clone http://llvm.org/git/compiler-rt.git
+  % git clone https://git.llvm.org/git/compiler-rt.git
 
 If you want to check out libomp (required for OpenMP support), run:
 
 .. code-block:: console
 
   % cd llvm/projects
-  % git clone http://llvm.org/git/openmp.git
+  % git clone https://git.llvm.org/git/openmp.git
 
 If you want to check out libcxx and libcxxabi (optional), run:
 
 .. code-block:: console
 
   % cd llvm/projects
-  % git clone http://llvm.org/git/libcxx.git
-  % git clone http://llvm.org/git/libcxxabi.git
+  % git clone https://git.llvm.org/git/libcxx.git
+  % git clone https://git.llvm.org/git/libcxxabi.git
 
 If you want to check out the Test Suite Source Code (optional), run:
 
 .. code-block:: console
 
   % cd llvm/projects
-  % git clone http://llvm.org/git/test-suite.git
+  % git clone https://git.llvm.org/git/test-suite.git
 
 Since the upstream repository is in Subversion, you should use ``git
 pull --rebase`` instead of ``git pull`` to avoid generating a non-linear history
 in your clone.  To configure ``git pull`` to pass ``--rebase`` by default on the
 master branch, run the following command:
 
 .. code-block:: console
 

 
 For developers to work with git-svn
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 To set up clone from which you can submit code using ``git-svn``, run:
 
 .. code-block:: console
 
-  % git clone http://llvm.org/git/llvm.git
+  % git clone https://git.llvm.org/git/llvm.git
   % cd llvm
   % git svn init https://llvm.org/svn/llvm-project/llvm/trunk --username=<username>
   % git config svn-remote.svn.fetch :refs/remotes/origin/master
   % git svn rebase -l  # -l avoids fetching ahead of the git mirror.
 
   # If you have clang too:
   % cd tools
-  % git clone http://llvm.org/git/clang.git
+  % git clone https://git.llvm.org/git/clang.git
   % cd clang
   % git svn init https://llvm.org/svn/llvm-project/cfe/trunk --username=<username>
   % git config svn-remote.svn.fetch :refs/remotes/origin/master
   % git svn rebase -l
 
 Likewise for compiler-rt, libomp and test-suite.
 
 To update this clone without generating git-svn tags that conflict with the

docs/Proposals/GitHubMove.rst

 There are two major variants for how to structure our Git repository: The
 "multirepo" and the "monorepo".
 
 Multirepo Variant
 -----------------
 
 This variant recommends moving each LLVM sub-project to a separate Git
 repository. This mimics the existing official read-only Git repositories
-(e.g., http://llvm.org/git/compiler-rt.git), and creates new canonical
+(e.g., https://git.llvm.org/git/compiler-rt.git), and creates new canonical
 repositories for each sub-project.
 
 This will allow the individual sub-projects to remain distinct: a
 developer interested only in compiler-rt can checkout only this repository,
 build it, and work in isolation of the other sub-projects.
 
 A key need is to be able to check out multiple projects (i.e. lldb+clang+llvm or
 clang+llvm+libcxx for example) at a specific revision.
As an example, it could look like the following::
   cmake path/to/monorepo -DLLVM_ENABLE_PROJECTS=clang
 
 .. _git-svn-mirror:
 
 Read/write sub-project mirrors
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 With the Monorepo, the existing single-subproject mirrors (e.g.
-http://llvm.org/git/compiler-rt.git) with git-svn read-write access would
+https://git.llvm.org/git/compiler-rt.git) with git-svn read-write access would
 continue to be maintained: developers would continue to be able to use the
 existing single-subproject git repositories as they do today, with *no changes
 to workflow*. Everything (git fetch, git svn dcommit, etc.) could continue to
 work identically to how it works today. The monorepo can be set-up such that the
 SVN revision number matches the SVN revision in the GitHub SVN-bridge.
 
 Living Downstream
 ^^^^^^^^^^^^^^^^^

 
 Checkout/Clone a Single Project, without Commit Access
 ------------------------------------------------------
 
 Except the URL, nothing changes. The possibilities today are::
 
   svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm
   # or with Git
-  git clone http://llvm.org/git/llvm.git
+  git clone https://git.llvm.org/git/llvm.git
 
 After the move to GitHub, you would do either::
 
   git clone https://github.com/llvm-project/llvm.git
   # or using the GitHub svn native bridge
   svn co https://github.com/llvm-project/llvm/trunk
 
 The above works for both the monorepo and the multirepo, as we'll maintain the
 existing read-only views of the individual sub-projects.
 
 Checkout/Clone a Single Project, with Commit Access
 ---------------------------------------------------
 
 Currently
 ^^^^^^^^^
 
 ::
 
   # direct SVN checkout
   svn co https://[e-mail]/svn/llvm-project/llvm/trunk llvm
   # or using the read-only Git view, with git-svn
-  git clone http://llvm.org/git/llvm.git
+  git clone https://git.llvm.org/git/llvm.git
   cd llvm
   git svn init https://llvm.org/svn/llvm-project/llvm/trunk --username=<username>
   git config svn-remote.svn.fetch :refs/remotes/origin/master
   git svn rebase -l  # -l avoids fetching ahead of the git mirror.
 
 Commits are performed using `svn commit` or with the sequence `git commit` and
 `git svn dcommit`.
 

 This checks out only compiler-rt and provides commit access using "svn commit",
 in the same way as it would do today.
 
 **Using a Subproject Git Nirror**
 
 You can use *git-svn* and one of the sub-project mirrors::
 
   # Clone from the single read-only Git repo
-  git clone http://llvm.org/git/llvm.git
+  git clone https://git.llvm.org/git/llvm.git
   cd llvm
   # Configure the SVN remote and initialize the svn metadata
   $ git svn init https://github.com/joker-eph/llvm-project/trunk/llvm —username=...
   git config svn-remote.svn.fetch :refs/remotes/origin/master
   git svn rebase -l
 
 In this case the repository contains only a single sub-project, and commits can
 be made using `git svn dcommit`, again exactly as we do today.
::
   svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm -r $REVISION
   cd llvm/tools
   svn co http://llvm.org/svn/llvm-project/clang/trunk clang -r $REVISION
   cd ../projects
   svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx -r $REVISION
 
 Or using git-svn::
 
-  git clone http://llvm.org/git/llvm.git
+  git clone https://git.llvm.org/git/llvm.git
   cd llvm/
   git svn init https://llvm.org/svn/llvm-project/llvm/trunk --username=<username>
   git config svn-remote.svn.fetch :refs/remotes/origin/master
   git svn rebase -l
   git checkout `git svn find-rev -B r258109`
   cd tools
-  git clone http://llvm.org/git/clang.git
+  git clone https://git.llvm.org/git/clang.git
   cd clang/
   git svn init https://llvm.org/svn/llvm-project/clang/trunk --username=<username>
   git config svn-remote.svn.fetch :refs/remotes/origin/master
   git svn rebase -l
   git checkout `git svn find-rev -B r258109`
   cd ../../projects/
-  git clone http://llvm.org/git/libcxx.git
+  git clone https://git.llvm.org/git/libcxx.git
   cd libcxx
   git svn init https://llvm.org/svn/llvm-project/libcxx/trunk --username=<username>
   git config svn-remote.svn.fetch :refs/remotes/origin/master
   git svn rebase -l
   git checkout `git svn find-rev -B r258109`
 
 Note that the list would be longer with more sub-projects.