No need to pass --valgrind to mysqltest anymore, the simple task of

creating an environment variable is handled directly from the perl code.  

mysql-test/mysql-test-run.pl

@@ -1749,6 +1749,11 @@ sub environment_setup () {
       print "Using IM_MYSQLD2_PORT       = $ENV{IM_MYSQLD2_PORT}\n";
     }
   }
+
+  # Create an environment variable to make it possible
+  # to detect that valgrind is being used from test cases
+  $ENV{'VALGRIND_TEST'}= $opt_valgrind;
+
 }
 
 
@@ -4009,11 +4014,6 @@ sub run_mysqltest ($) {
     mtr_add_arg($args, "--big-test");
   }
 
-  if ( $opt_valgrind )
-  {
-    mtr_add_arg($args, "--valgrind");
-  }
-
   if ( $opt_compress )
   {
     mtr_add_arg($args, "--compress");