Fix multiple inclusion guards to match new pathnames

Change-Id: Id7735be1d75bc315733b1773fba45c1deb8ace43
diff --git a/runtime/gc/heap.h b/runtime/gc/heap.h
index e6c9221..630d063 100644
--- a/runtime/gc/heap.h
+++ b/runtime/gc/heap.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef ART_SRC_GC_HEAP_H_
-#define ART_SRC_GC_HEAP_H_
+#ifndef ART_RUNTIME_GC_HEAP_H_
+#define ART_RUNTIME_GC_HEAP_H_
 
 #include <iosfwd>
 #include <string>
@@ -609,4 +609,4 @@
 }  // namespace gc
 }  // namespace art
 
-#endif  // ART_SRC_GC_HEAP_H_
+#endif  // ART_RUNTIME_GC_HEAP_H_