Set amcancrosscompare to true for hash

This was missed in the refactoring in patch ce62f2f2a0, which thus
created a regression.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Mark Dilger <mark.dilger@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/E1tngY6-0000UL-2n%40gemulon.postgresql.org

src/backend/access/hash/hash.c

@@ -65,7 +65,7 @@ hashhandler(PG_FUNCTION_ARGS)
 	amroutine->amcanorder = false;
 	amroutine->amcanorderbyop = false;
 	amroutine->amcanhash = true;
-	amroutine->amcancrosscompare = false;
+	amroutine->amcancrosscompare = true;
 	amroutine->amcanbackward = true;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = false;