Add REG_NOSUB as we only need matched results.

servers/slapd/filterentry.c

@@ -396,7 +396,7 @@ test_substring_filter(
 	/* compile the regex */
 	Debug( LDAP_DEBUG_FILTER, "test_substring_filter: regcomp pat: %s\n",
 		pat, 0, 0 );
-	if ((rc = regcomp(&re, pat, REG_EXTENDED))) {
+	if ((rc = regcomp(&re, pat, REG_EXTENDED|REG_NOSUB))) {
 		char error[512];
 
 		regerror(rc, &re, error, sizeof(error));