pg_upgrade: avoid ALTER COLUMN TYPE on inherited columns

This only affects upgrades from 8.3 currently, and is harmless as the
child just generates an error in the script, but we should get it right
in case we ever need this for more complex uses.

Per report from Peter Eisentraut

contrib/pg_upgrade/version_old_8_3.c

@@ -325,6 +325,8 @@ old_8_3_rebuild_tsvector_tables(ClusterInfo *cluster, bool check_mode)
 								"WHERE	c.relkind = 'r' AND "
 								"		c.oid = a.attrelid AND "
 								"		NOT a.attisdropped AND "
+		/* child attribute changes are processed by the parent */
+								"		a.attinhcount = 0 AND "
 								"		a.atttypid = 'pg_catalog.tsvector'::pg_catalog.regtype AND "
 								"		c.relnamespace = n.oid AND "
 		/* exclude possible orphaned temp tables */
@@ -346,6 +348,8 @@ old_8_3_rebuild_tsvector_tables(ClusterInfo *cluster, bool check_mode)
 								"WHERE	c.relkind = 'r' AND "			\
 								"		c.oid = a.attrelid AND "		\
 								"		NOT a.attisdropped AND "		\
+		/* child attribute changes are processed by the parent */		\
+								"		a.attinhcount = 0 AND "			\
 								"		a.atttypid = 'pg_catalog.tsvector'::pg_catalog.regtype AND " \
 								"		c.relnamespace = n.oid AND "	\
 								"       n.nspname !~ '^pg_' AND "		\