Report mutex errors for each different mutex even if the call stacks are identical.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@10681 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/drd/drd_error.c b/drd/drd_error.c
index 2e02597..74291f5 100644
--- a/drd/drd_error.c
+++ b/drd/drd_error.c
@@ -207,6 +207,12 @@
       return dri1->access_type == dri2->access_type
 	     && dri1->size == dri2->size;
    }
+   case MutexErr:
+   {
+      const MutexErrInfo* const mei1 = VG_(get_error_extra)(e1);
+      const MutexErrInfo* const mei2 = VG_(get_error_extra)(e2);
+      return mei1->mutex == mei2->mutex;
+   }
    default:
       return True;
    }