* Preliminary support for m88k-coff.

	* Preliminary support for m88k-coff.
	* configure.in (m88k-*-coff*): New target.  Use coffbfd and
	m88kcoff.
	* config/m88kcoff.mt: New file.
	* read.c (lex_type): New macro LEX_AT to set lex type of '@'.
	(pseudo_set): Handle difference of symbols in different fragments
	by saving the entire expression as the value of the symbol.
	* symbols.c (resolve_symbol_value): Resolve difference
	expressions.
	* config/obj-coffbfd.c (obj_pseudo_table): If TC_M88K, accept
	"sdef" as a synonym for "def".
	* config/obj-coffbfd.h: If TC_M88K, include coff/m88k.h and set
	TARGET_FORMAT.
	(S_IS_LOCAL): Any symbol which includes \001 in the name is local.
	* config/tc-m88k.c, config/tc-m88k.h: Numerous changes to bring
	m88k port up to date, and to add COFF support.