[clang] [clang][OpenMP][test] Use -fopenmp=libomp explicitly in clang driver test (PR #209082)

[Kyungtak Woo via cfe-commits]

https://github.com/kevinwkt created https://github.com/llvm/llvm-project/pull/209082

Explicitly pass -fopenmp=libomp in the test to make it robust against downstream configurations where the default OpenMP runtime is set to something else (e.g., libgomp). Seems this is in alignment with other tests in `clang/test/Driver`. 

>From bcd6a2a667ce2e5f598f27c62753c3e0bd15bfcd Mon Sep 17 00:00:00 2001
From: Kyungtak Woo <kevinwkt at google.com>
Date: Mon, 13 Jul 2026 05:12:48 +0000
Subject: [PATCH] fix: explicit libomp pass for driver test

---
 clang/test/Driver/amdgpu-openmp-gpu-max-threads-per-block.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/test/Driver/amdgpu-openmp-gpu-max-threads-per-block.c b/clang/test/Driver/amdgpu-openmp-gpu-max-threads-per-block.c
index ba5dd4c24a0bd..85bf4fc75dca3 100644
--- a/clang/test/Driver/amdgpu-openmp-gpu-max-threads-per-block.c
+++ b/clang/test/Driver/amdgpu-openmp-gpu-max-threads-per-block.c
@@ -1,5 +1,5 @@
 // Test that --gpu-max-threads-per-block is not ignored by openmp.
-// RUN: %clang -### --target=x86_64-unknown-linux-gnu -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa \
+// RUN: %clang -### --target=x86_64-unknown-linux-gnu -fopenmp=libomp -fopenmp-targets=amdgcn-amd-amdhsa \
 // RUN:   --offload-arch=gfx906 -nogpulib --gpu-max-threads-per-block=256 %s 2>&1 | FileCheck %s
 
 // CHECK: "-cc1" "-triple" "amdgcn-amd-amdhsa"