Automerged (cherrypicked) cset from 5.6:

zhenxing.he@sun.com-20101117085902-n9gfvlkmm44t38y0
  
This takes care of valgrind warnings in 5.5 that exhibit
the same trace as in BUG#11763879 (BUG#56649).

sql/rpl_handler.h

@@ -73,7 +73,10 @@ class Delegate {
     while (info && info->observer != observer)
       info= iter++;
     if (info)
+    {
       iter.remove();
+      delete info;
+    }
     else
       ret= TRUE;
     unlock();