OpenMP test case fails if Clang/LLVM source directory contains the 'ref' string.

If the ``Clang\LLVM`` source directory contains the ``ref`` string like: ``[..]/llvm-ref/llvm-project``, the test case
`Clang :: OpenMP/declare_target_only_one_side_compilation.cpp`
fails with the following output:
```
# .---command stderr------------
# | [..]/llvm-ref/llvm-project/clang/test/OpenMP/declare_target_only_one_side_compilation.cpp:66:16: error: DEVICE-NOT: excluded string found in input
# | // DEVICE-NOT: ref
# | ^
# | :21:55: note: found here
# | !3 = !{!"clang version 22.0.0git ([..]/llvm-ref/llvm-project/clang 76ec25f729fcc7ae576caf21293cc393e68e7cf7)"}
# | ^~~
# |
# | Input file:
# | Check file: [..]/llvm-ref/llvm-project/clang/test/OpenMP/declare_target_only_one_side_compilation.cpp
# |
# | -dump-input=help explains the following input dump.
# |
# | Input was:
# | <<<<<<
# | .
# | .
# | .
# | 16: !llvm.ident = !{!3}
# | 17:
# | 18: !0 = !{i32 1, !"wchar_size", i32 4}
# | 19: !1 = !{i32 7, !"openmp", i32 51}
# | 20: !2 = !{i32 7, !"openmp-device", i32 51}
# | 21: !3 = !{!"clang version 22.0.0git ([..]/llvm-ref/llvm-project/clang 76ec25f729fcc7ae576caf21293cc393e68e7cf7)"}
# | not:66 !~~ error: no match expected
# | >>>>>>
# `-----------------------------

```