Cleanup: nullify pointer after memory freeing

[AndreyChurbanov]

Summary

Static library crashed sometimes on tests those cause library to repeatedly start up and shut down with affinity enabled (e.g. non-OMP thread creates / joins many OMP threads one by one).

[jlpeyton]

LGTM

openmp/trunk/runtime/src/kmp_affinity.h

for (int i = hier_depth - 1; i >= 0; --i) {
       ++level;
     }
   }
 
   hierarchy_info()
       : maxLevels(7), depth(1), uninitialized(not_initialized), resizing(0) {}
 
   void fini() {
-    if (!uninitialized && numPerLevel)
+    if (!uninitialized && numPerLevel) {
       __kmp_free(numPerLevel);
+      numPerLevel = NULL;
+      uninitialized = not_initialized;
+    }
   }
 
   void init(AddrUnsPair *adr2os, int num_addrs) {
     kmp_int8 bool_result = KMP_COMPARE_AND_STORE_ACQ8(
         &uninitialized, not_initialized, initializing);
     if (bool_result == 0) { // Wait for initialization
       while (TCR_1(uninitialized) != initialized)
         KMP_CPU_PAUSE();