Ignore AFTER triggers sorting after z_repack_trigger

They are not a problem, and they fore after the BEFORE trigger anyway.

To be checked against more PostgreSQL versions.

lib/pg_repack.sql.in

@@ -219,6 +219,7 @@ CREATE FUNCTION repack.conflicted_triggers(oid) RETURNS SETOF name AS
 $$
 SELECT tgname FROM pg_trigger
  WHERE tgrelid = $1 AND tgname >= 'z_repack_trigger'
+ AND (tgtype & 2) = 2      -- BEFORE trigger
  ORDER BY tgname;
 $$
 LANGUAGE sql STABLE STRICT;