[clang] Robustify openmp test (#69739)

If the source path contains 'alias' this would spuriously fail. Be more
specific about not wanting global aliases

Author: urnathan

clang/test/OpenMP/declare_variant_device_kind_codegen.cpp

@@ -80,7 +80,8 @@
 
 // expected-no-diagnostics
 
-// CHECK-NOT: alias
+// Verify no unexpected global symbol aliasing
+// CHECK-NOT: @{{[^ ]+}} = {{.*}}alias
 
 // CHECK-NOT: ret i32 {{1|4|81|84}}
 // CHECK-DAG: declare {{.*}}i32 @_Z5bazzzv()