[OpenMP][omptest] Fix CMake target properties (#176802)

Fix visibility of target properties:
 * INCLUDE_DIRECTORIES
 * COMPILE_DEFINITIONS

implicitly pulled in from `default_gtest`.

Fixes: https://github.com/llvm/llvm-project/pull/159416
GitOrigin-RevId: 696b91aeb7e55d5fbc82b2e6a625f2a7ca4a6911
1 file changed