Merge branch 'FindOpenMP-avoid-warning-in-check' into release-3.12

Merge-request: !2176

Modules/FindOpenMP.cmake

@@ -126,7 +126,7 @@ set(OpenMP_C_CXX_TEST_SOURCE
 #include <omp.h>
 int main() {
 #ifdef _OPENMP
-  int n = omp_get_max_threads();
+  omp_get_max_threads();
   return 0;
 #else
   breaks_on_purpose