Fix allocation tracking race

Need to instrument the stubs before calling
Heap::SetAlloctrackingEnabled or else we can get this DCHECK failing
DCHECK(!IsAllocTrackingEnabled())

Change-Id: I1fb5df217a2785baf22b4f57887cd323f13f0973
diff --git a/runtime/gc/allocation_record.cc b/runtime/gc/allocation_record.cc
index 83e5bad..4de5388 100644
--- a/runtime/gc/allocation_record.cc
+++ b/runtime/gc/allocation_record.cc
@@ -238,9 +238,12 @@
                 << records->max_stack_depth_ << " frames, taking up to "
                 << PrettySize(sz * records->alloc_record_max_) << ")";
       heap->SetAllocationRecords(records);
-      heap->SetAllocTrackingEnabled(true);
     }
     Runtime::Current()->GetInstrumentation()->InstrumentQuickAllocEntryPoints();
+    {
+      MutexLock mu(self, *Locks::alloc_tracker_lock_);
+      heap->SetAllocTrackingEnabled(true);
+    }
   } else {
     {
       MutexLock mu(self, *Locks::alloc_tracker_lock_);