[cmake] Add all subprojects to LLVM_ALL_PROJECTS

[smeenai]

Summary

Make LLVM_ALL_PROJECTS reflect all top-level directories in the monorepo
rather than an arbitrary subset. clang-tools-extra is technically
unnecessary since it gets enabled by clang, but having it there for
consistency shouldn't hurt either.

[smeenai]

I'm putting this up for review just in case there's some potential for breakage I'm not seeing. Note that all these directories are present in the old monorepo as well, so it shouldn't break anyone who's still on that.

[phosek]

LGTM

llvm/trunk/CMakeLists.txt

if(DYLD_LIBRARY_PATH)
     endforeach()
   endif()
 endif()
 
 # Side-by-side subprojects layout: automatically set the
 # LLVM_EXTERNAL_${project}_SOURCE_DIR using LLVM_ALL_PROJECTS
 # This allows an easy way of setting up a build directory for llvm and another
 # one for llvm+clang+... using the same sources.
-set(LLVM_ALL_PROJECTS "clang;libcxx;libcxxabi;libunwind;lldb;compiler-rt;lld;polly;debuginfo-tests;openmp")
+set(LLVM_ALL_PROJECTS "clang;clang-tools-extra;compiler-rt;debuginfo-tests;libclc;libcxx;libcxxabi;libunwind;lld;lldb;llgo;llvm;openmp;parallel-libs;polly;pstl")
 set(LLVM_ENABLE_PROJECTS "" CACHE STRING
   "Semicolon-separated list of projects to build (${LLVM_ALL_PROJECTS}), or \"all\".")
 if( LLVM_ENABLE_PROJECTS STREQUAL "all" )
   set( LLVM_ENABLE_PROJECTS ${LLVM_ALL_PROJECTS})
 endif()
 
 # LLVM_ENABLE_PROJECTS_USED is `ON` if the user has ever used the
 # `LLVM_ENABLE_PROJECTS` CMake cache variable.  This exists for