* config/tc-m68k.c (m68k_ip): Accept 'B' as a size for an

	* config/tc-m68k.c (m68k_ip): Accept 'B' as a size for an
	immediate value.
	(md_assemble): If the size is 'B', set fx_signed.
	(md_apply_fix_2): Use fx_signed when checking for overflow.

	* write.h (struct fix): Add fx_signed field.
	* write.c (fix_new_internal): Initialize fx_no_overflow and
	fx_signed fields.
	(fixup_segment): Use fx_signed when checking for overflow.
	* config/obj-coff.c (fixup_segment): Check fx_no_overflow and
	fx_signed when checking for overflow.