[compiler-rt] [libc] [libcxx] [libcxxabi] [libunwind] [llvm] [openmp] [Runtimes] Introduce variables containing resource dir paths (PR #177953)

[Michael Kruse via llvm-commits]

================

----------------
Meinersbur wrote:

1. Functions in this file get the subdir within a $PREFIX. This is not necessarily the resource dir, but could also be CMAKE_INSTALL_PREFIX ("sysroot"), or the Clang build directory.

2. "CompilerRTPath" referes to the "compiler-rt" project. This is not meant to be specific to compiler-rt.

https://github.com/llvm/llvm-project/pull/177953