[openmp] [test] [runtime] Do not include alloca.h on NetBSD

[mgorny]

Summary

On NetBSD, alloca() is in stdlib.h and there is no alloca.h. Adjust
the includes appopriately.

[krytarowski]

I propose to include (c)stdlib(.h) for everybody. And include alloca.h for everybody except NetBSD, FreeBSD, DragonFly and OpenBSD.

[mgorny]

Updated as requested by @krytarowski.

[devnexen]

Just to add to the conversation neither does FreeBSD.

openmp/trunk/runtime/test/ompt/misc/interoperability.cpp

 // RUN: %libomp-cxx-compile-and-run | %sort-threads | FileCheck %s
 // REQUIRES: ompt
 
 #include <iostream>
 #include <thread>
+#if !defined(__NetBSD__)
 #include <alloca.h>
+#else
+#include <cstdlib>
+#endif
 
 #include "callback.h"
 #include "omp.h"
 
 int condition = 0;
 
 void f() {
   // Call OpenMP API function to force initialization of OMPT.