tm.texi (DWARF_ALT_FRAME_RETURN_COLUMN): Do not require DWARF_FRAME_RETURN_COLUMN to be a general register.

gcc/
	* doc/tm.texi (DWARF_ALT_FRAME_RETURN_COLUMN): Do not require
	DWARF_FRAME_RETURN_COLUMN to be a general register.
	* dwarf2out.c (init_return_column_size): New function, split from...
	(expand_builtin_init_dwarf_reg_sizes): ...here.  Allow both
	DWARF_FRAME_RETURN_COLUMN and DWARF_ALT_FRAME_RETURN_COLUMN
	to be nongeneral registers.
	* config/m68k/m68k.h (DWARF_FRAME_REGNUM): Only map FP and
	integer registers.
	(DWARF_FRAME_REGISTERS, DWARF_FRAME_RETURN_COLUMN): Define.
	(DWARF_ALT_FRAME_RETURN_COLUMN): Define.

From-SVN: r121593