[llvm] [offload] [test] Use test compiler ID rather than host (PR #124408)

[Michał Górny via llvm-commits]

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@@ -1,6 +1,6 @@
 # CMakeLists.txt file for unit testing OpenMP offloading runtime library.
-if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "Clang" OR
-   CMAKE_CXX_COMPILER_VERSION VERSION_LESS 6.0.0)
+if(NOT OPENMP_TEST_COMPILER_ID STREQUAL "Clang" OR
+   OPENMP_TEST_COMPILER_VERSION VERSION_LESS 6.0.0)
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mgorny wrote:

Yeah, I was kinda surprised to see it. It's kinda true you usually can't test runtimes without Clang, but not sure if runtimes really need to explicitly assert that.

https://github.com/llvm/llvm-project/pull/124408