Add Heap::RunningOnValgrind and call it from the spaces.

Makes it easier to disable valgrind support.

Change-Id: I1bde792f1b76a2dd968fa03c6142e92fcc3670b0
diff --git a/runtime/gc/space/dlmalloc_space.cc b/runtime/gc/space/dlmalloc_space.cc
index 0597422..30c2edb 100644
--- a/runtime/gc/space/dlmalloc_space.cc
+++ b/runtime/gc/space/dlmalloc_space.cc
@@ -60,7 +60,7 @@
 
   // Everything is set so record in immutable structure and leave
   byte* begin = mem_map->Begin();
-  if (RUNNING_ON_VALGRIND > 0) {
+  if (Runtime::Current()->GetHeap()->RunningOnValgrind()) {
     return new ValgrindMallocSpace<DlMallocSpace, void*>(
         name, mem_map, mspace, begin, end, begin + capacity, growth_limit, initial_size);
   } else {