combine.c (gen_lowpart_for_combine): Update handling of subregs_of_mode

combine.c (gen_lowpart_for_combine): Update handling of subregs_of_mode

	* combine.c (gen_lowpart_for_combine): Update handling of
	subregs_of_mode
	* flow.c (life_analysis, mark_used_regs): Likewise.
	* regclass.c (subregs_of_mode): Turn into single bitmap.
	(cannot_change-mode_set_regs, invalid_mode_change_p): Update
	dealing with subregs_of_mode
	* regs.h (subregs_of_mode): Update prototype.

From-SVN: r63552