[llvm] [openmp] Deprecate LLVM_ENABLE_PROJECTS in favor of LLVM_ENABLE_RUNTIMES (PR #124711)

[Michael Kruse via llvm-commits]

Meinersbur wrote:

I have been overseeing something.

There is a second set of build instructions at
https://github.com/llvm/llvm-project/blob/main/openmp/runtime/src/CMakeLists.txt#L378-L383
Actually, there are three:
https://github.com/llvm/llvm-project/blob/main/openmp/runtime/src/CMakeLists.txt#L400-L406

However, they are emitted into `${CMAKE_CURRENT_BINARY_DIR}` (which is `runtimes/runtimes-bins/openmp/runtime/src`) where flang does not find them by default, so the regression tests add another `-J` flag to the compiler invocation. `ninja check-flang` was still failing with all the OpenMP tests because `add_dependence(check-flang runtimes)` (or similar) is missing.


https://github.com/llvm/llvm-project/pull/124711