Use pg_dump's --quote-all-identifiers option in pg_upgrade.

This helps guard against changes in the set of reserved keywords from
one version to another.  In theory it should only be an issue if we
de-reserve a keyword in a newer release, since that can create the type
of problem shown in bug #8128.

Back-patch to 9.1 where the --quote-all-identifiers option was added.

contrib/pg_upgrade/dump.c

@@ -22,7 +22,8 @@ generate_old_dump(void)
 	 */
 	exec_prog(true,
 			  SYSTEMQUOTE "\"%s/pg_dumpall\" --port %d --username \"%s\" "
-			  "--schema-only --binary-upgrade -f \"%s/" ALL_DUMP_FILE "\""
+			  "--schema-only --quote-all-identifiers --binary-upgrade "
+			  "-f \"%s/" ALL_DUMP_FILE "\""
 			  SYSTEMQUOTE, new_cluster.bindir, old_cluster.port, os_info.user, os_info.cwd);
 	check_ok();
 }