[CMake] Add an LLVM_ENABLE_MODULE_DEBUGGING flag for building with -gmodules.
This flag is only effective in builds with debug info and modules.
The default is On for Darwin only.

rdar://problem/27019000

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274244 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed