Ooops, missed that a couple of contrib modules have calls to byteacmp.

Add bytea.h inclusions as needed.  Some of the contrib regression tests
need to be de-hexified, too.  Per buildfarm.

contrib/btree_gin/expected/bytea.out

@@ -1,4 +1,6 @@
 set enable_seqscan=off;
+-- ensure consistent test output regardless of the default bytea format
+SET bytea_output TO escape;
 CREATE TABLE test_bytea (
 	i bytea
 );