Fix cpplint whitespace/comments issues

Change-Id: Iae286862c85fb8fd8901eae1204cd6d271d69496
diff --git a/runtime/gc/collector/mark_sweep.h b/runtime/gc/collector/mark_sweep.h
index 34136d4..d386fd6 100644
--- a/runtime/gc/collector/mark_sweep.h
+++ b/runtime/gc/collector/mark_sweep.h
@@ -424,7 +424,7 @@
 
   bool clear_soft_references_;
 
-  friend class AddIfReachesAllocSpaceVisitor; // Used by mod-union table.
+  friend class AddIfReachesAllocSpaceVisitor;  // Used by mod-union table.
   friend class CheckBitmapVisitor;
   friend class CheckObjectVisitor;
   friend class CheckReferenceVisitor;