CkArray: Allow broadcasts of ckDestroy

Deliver array broadcasts to local elements in reverse order, starting at
the end of the local element vector and proceeding to the beginning.
This pattern allows the target function of the broadcast to destroy the
array element without invalidating the remainder of the iteration space
for the local element vector.

Author: rbuch

src/ck-core/ckarray.C

@@ -1697,10 +1697,12 @@ void CkArray::recvBroadcast(CkMessage* m)
     if (zc_msgtype == CMK_ZC_BCAST_RECV_DONE_MSG) {
       updateTagArray(env, localElemVec.size());
     }
-    for (unsigned int i = 0; i < len; ++i)
+    // Deliver in reverse order in case the target method destroys and removes
+    // the element from localElemVec
+    for (int i = len - 1; i >= 0; --i)
     {
       bool doFree = false;
-      if (stableLocations && i == len - 1)
+      if (stableLocations && i == 0)
         doFree = true;
       // Do not free if CMK_ZC_BCAST_RECV_DONE_MSG, since it'll be freed by the
       // first element during CMK_ZC_BCAST_ALL_DONE_MSG