Bug #12373916 MTR SHOULD FLAG PRESENCE OF VALGRIND MEMORY LEAK REPORTS IN A CLEARER WAY

Fix: it only worked if some worker had valgrind report from its last test
Flag has to be set both places where report is printed

mysql-test/mysql-test-run.pl

@@ -5677,6 +5677,7 @@ sub valgrind_exit_reports() {
                         @culprits);
             mtr_print_line();
             print ("$valgrind_rep\n");
+            $found_err= 1;
             $err_in_report= 0;
           }
           # Make ready to collect new report