[openmp][cmake] Don't glob for build dependencies (#165231)

LLVM's cmake standard explicitly lists all source in the CMakeLists.txt.
Remove globbing for source files in OpenMP's CMakeLists.txt.

Also see #4899, #71404, https://reviews.llvm.org/D79906,
https://reviews.llvm.org/D31363, https://reviews.llvm.org/D61275,
https://discourse.llvm.org/t/cmake-builds-clang/11536, and CMake's note
at https://cmake.org/cmake/help/latest/command/file.html#glob. Two
reasons to not glob for source files is that it breaks bisecting and
incremental builds. Renaming a file, reverting or checking out an older
reversion where a newly added source file disappears again will not
trigger a CMake configure step and make the build fail because of a
non-existing source file.

GitOrigin-RevId: 20a742cb4fa0e7d133dac2aa6433dc9edb7ae8f4
2 files changed