The last target using this was i960, which was removed many years ago,
so there's no reason to keep it.

gcc/ChangeLog:

2015-11-14  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* gsyms.h (enum sdb_type): Remove code for
	EXTENDED_SDB_BASIC_TYPES.
	(enum sdb_masks): Likewise.
	* sdbout.c (plain_type_1): Likewise.
	* system.h: Poison EXTENDED_SDB_BASIC_TYPES macro.

From-SVN: r230389