Hold heap bitmap lock in Heap::GetObjectsAllocated

Fixes a race condition where add and remove space could cause a crash
when we iterated over the spaces.

TODO: Add a spaces lock or something to guard against this.

(cherry picked from commit a395c0a492079d86b312c9edc796d63001576954)

Bug: 21031927

Change-Id: I7f0d558316f8e9d9f22ffd182e8666355bf50d47
diff --git a/runtime/native/java_lang_Thread.cc b/runtime/native/java_lang_Thread.cc
index be7022e..6569d83 100644
--- a/runtime/native/java_lang_Thread.cc
+++ b/runtime/native/java_lang_Thread.cc
@@ -84,6 +84,7 @@
     case kWaitingInMainDebuggerLoop:      return kJavaWaiting;
     case kWaitingForDebuggerSuspension:   return kJavaWaiting;
     case kWaitingForDeoptimization:       return kJavaWaiting;
+    case kWaitingForGetObjectsAllocated:  return kJavaWaiting;
     case kWaitingForJniOnLoad:            return kJavaWaiting;
     case kWaitingForSignalCatcherOutput:  return kJavaWaiting;
     case kWaitingInMainSignalCatcherLoop: return kJavaWaiting;