[OMPT] Add synchronization to threads_nested.c testcase

The testcase potentially fails when a thread is reused.
The added synchronization makes sure this does not happen.

Patch provided by Simon Convent

Differential Revision: https://reviews.llvm.org/D48932

llvm-svn: 336326

openmp/runtime/test/ompt/misc/threads_nested.c

@@ -4,14 +4,16 @@
 #include <omp.h>
 
 int main() {
+
+  int condition = 0;
   int x = 0;
   omp_set_nested(1);
 #pragma omp parallel num_threads(2)
   {
 #pragma omp parallel num_threads(2)
     {
-#pragma omp atomic
-      x++;
+      OMPT_SIGNAL(condition);
+      OMPT_WAIT(condition, 4);
     }
   }