genmodes.c: Include hashtab.h.

	* genmodes.c: Include hashtab.h.
	(modes_by_name, hash_mode, eq_mode, struct mode_adjust)
	(adj_bytesize, adj_alignment, adj_format, new_adjust)
	(_ADD_ADJUST, ADJUST_BYTESIZE, ADJUST_ALIGNMENT, ADJUST_FORMAT)
	(print_maybe_const_decl, emit_mode_adjustments): New.
	(known_modes): Rename to modes.
	(find_mode): Kill class argument; look up in hash table.
	(new_mode): Insert into hash table also.
	(new_adjust): New.
	(reset_float_format, make_partial_integer_mode)
	(make_vector_mode): Tweak error reporting.
	(reset_float_format): Correct type of fourth argument.
	(emit_insn_modes_h): Add #defines to help make mode_size,
	mode_base_align, and real_format_for_mode conditionally const.
	(emit_mode_size, emit_mode_base_align): Use print_maybe_const_decl.
	(emit_real_format_for_mode): Likewise, but temporarily disabled.
	(emit_insn_modes_c): Call emit_mode_adjustments.
	(main): Initialize modes_by_name.
	* Makefile.in: Update dependencies.
	* machmode.def: Document EXPR arguments and new ADJUST_* statements.
	* machmode.h: Use CONST_MODE_SIZE and CONST_MODE_BASE_ALIGN in
	declarations of mode_size and mode_base_align.  Declare
	init_adjust_machine_modes.
	* toplev.c (backend_init): Call init_adjust_machine_modes.

From-SVN: r72534