dialplan: fix shm leak when parsing invalid regex

Upon (re)load, if the subst or repl columns contain expressions which
fail to compile, OpenSIPS will leak shared memory.

Reported by miko95 on GitHub
Closes issue #307
(cherry picked from commit 72028d2)

modules/dialplan/dp_db.c

@@ -435,6 +435,7 @@ dpl_node_t * build_rule(db_val_t * values)
 	return new_rule;
 
 err:
+	if(match_comp)	wrap_pcre_free(match_comp);
 	if(subst_comp)	wrap_pcre_free(subst_comp);
 	if(repl_comp)	repl_expr_free(repl_comp);
 	if(new_rule)	destroy_rule(new_rule);