Make sure no error message is printed when pthread_mutex_trylock() is called on a non-recursive mutex from the thread that holds a lock on the mutex.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@7769 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/exp-drd/drd_clientreq.c b/exp-drd/drd_clientreq.c
index c2a3485..5076688 100644
--- a/exp-drd/drd_clientreq.c
+++ b/exp-drd/drd_clientreq.c
@@ -147,7 +147,7 @@
 
   case VG_USERREQ__PRE_MUTEX_LOCK:
     if (thread_enter_synchr(drd_tid) == 0)
-      drd_pre_mutex_lock(arg[1], arg[2]);
+      drd_pre_mutex_lock(arg[1], arg[2], arg[3]);
     break;
 
   case VG_USERREQ__POST_MUTEX_LOCK: