* targets.c (enum bfd_endian): Define.

	* targets.c (enum bfd_endian): Define.
	(bfd_target): Rename byteorder_big_p to byteorder, and change it
	from boolean to enum bfd_endian.  Change header_byteorder_big_p
	correspondingly.
	* bfd-in.h (bfd_big_endian, bfd_little_endian): New macros.
	(bfd_header_big_endian, bfd_header_little_endian): New macros.
	* bfd-in2.h: Rebuild.
	* All targets: Change initialization of byteorder and
	header_byteorder to use enum bfd_endian values rather than
	booleans.
	* All files: Change all references to byteorder_big_p and
	header_byteorder_big_p to use new bfd_*_endian macros.