* gdbtypes.h (struct language_defn): Add forward declaration.

	(lookup_typename): Add LANGUAGE and GDBARCH parameters.
	(lookup_unsigned_typename): Likewise.
	(lookup_signed_typename): Likewise.
	* gdbtypes.c (lookup_typename): Add LANGUAGE and GDBARCH parameters.
	Use them instead of current_language and current_gdbarch.
	(lookup_unsigned_typename): Add LANGUAGE and GDBARCH parameters.
	Pass them to lookup_typename.
	(lookup_signed_typename): Likewise.

	* c-exp.y: Pass parse_language and parse_gdbarch to
	lookup_unsigned_typename and lookup_signed_typename.
	* objc-exp.y: Likewise.
	* m2-exp.y: Pass parse_language and parse_gdbarch to lookup_typename.

	* c-lang.c (evaluate_subexp_c): Pass expression language and
	gdbarch to lookup_typename.
	* printcmd.c (printf_command): Pass current language and
	gdbarch to lookup_typename.
	* python/python-type.c (typy_lookup_typename): Likewise.
	Include "language.h".