[Docs] Remove SVN checkout from LLDB build steps

[jryans]

Summary

This removes several older paragraphs in the LLDB build steps for Unix systems
which suggested checking out various components via SVN. Since there's a
separate page about getting the LLDB source which only mentions Git, it seems
appropriate to remove this older info from the build docs.

[JDevlieghere]

lldb/docs/resources/build.rst

238–239

Let's remove the next paragraph as well and remove the whole section.

[jryans]

Updated to remove the whole section

[jryans]

Thanks for the review @JDevlieghere! 😄 This should be ready for another look. I don't have commit access yet, so assuming it's approved, please commit when you have time.

lldb/docs/resources/build.rst

238–239

Makes sense to me! I have updated to do so.

[JDevlieghere]

LGTM. Thank you!

lldb/docs/resources/build.rst

::
 
   > pkg install swig python
 
 On NetBSD one might run:
 
 ::
 
   > pkgin install swig python27 cmake ninja-build
 
-
-**Building LLDB**
-
-We first need to checkout the source trees into the appropriate locations. Both
-Clang and LLDB build as subprojects of LLVM. This means we will be checking out
-the source for both Clang and LLDB into the tools subdirectory of LLVM. We will
-be setting up a directory hierarchy looking something like this:
-
-::
-
-                  llvm
-                  |
-                  `-- tools
-                      |
-                      +-- clang
-                      |
-                      `-- lldb
-
-For reference, we will call the root of the LLVM project tree $llvm, and the
-roots of the Clang and LLDB source trees $clang and $lldb respectively.
-
-Change to the directory where you want to do development work and checkout
-LLVM:
-
-::
-
-  > svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm
-
-
-Now switch to LLVM’s tools subdirectory and checkout both Clang and LLDB:
-
-::
-
-  > cd $llvm/tools
-  > svn co http://llvm.org/svn/llvm-project/cfe/trunk clang
-  > svn co http://llvm.org/svn/llvm-project/lldb/trunk lldb
-
-In general, building the LLDB trunk revision requires trunk revisions of both
-LLVM and Clang.
-
-It is highly recommended that you build the system out of tree. Create a second
-build directory and configure the LLVM project tree to your specifications as
-outlined in LLVM’s Getting Started Guide. A typical build procedure might be:
-
-::
-
-  > cd $llvm/..
-  > mkdir build
-  > cd build
-
 **To build with CMake**
 
-
 Using CMake is documented on the `Building LLVM with CMake
 <http://llvm.org/docs/CMake.html>`_ page. Building LLDB is possible using one
 of the following generators:
 
 * Ninja
 * Unix Makefiles
 
 **Using CMake + Ninja**