[testcase][OpenMP] Fix the testcase error of check-all when DCLANG_DEFAULT_OPENMP_RUNTIME is not libomp

When DCLANG_DEFAULT_OPENMP_RUNTIME is set to libgomp, there is some check-all error.
The expected CHECK result only displays when fopenmp=libomp is specified explicitly.

Differential Revision: https://reviews.llvm.org/D136239

Author: zixuan-wu

clang/test/Driver/fopenmp.c

@@ -140,7 +140,7 @@
 // CHECK-LD-STATIC-IOMP5-NO-BDYNAMIC: "-{{B?}}static" {{.*}} "-liomp5"
 // CHECK-LD-STATIC-IOMP5-NO-BDYNAMIC-NOT: "-Bdynamic"
 //
-// RUN: %clang -target x86_64-linux-gnu -fopenmp -fopenmp-enable-irbuilder -c %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CC1-OPENMPIRBUILDER
+// RUN: %clang -target x86_64-linux-gnu -fopenmp=libomp -fopenmp-enable-irbuilder -c %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-CC1-OPENMPIRBUILDER
 //
 // CHECK-CC1-OPENMPIRBUILDER: "-cc1"
 // CHECK-CC1-OPENMPIRBUILDER-SAME: "-fopenmp"

clang/test/Index/openmp-tile.c

@@ -1,4 +1,4 @@
-// RUN: c-index-test -test-load-source local %s -fopenmp -fopenmp-version=51 | FileCheck %s
+// RUN: c-index-test -test-load-source local %s -fopenmp=libomp -fopenmp-version=51 | FileCheck %s
 
 void test() {
 #pragma omp tile sizes(5)