* dwarf2-frame.c (dwarf2_frame_ops init_reg): Add "next_frame"

	* dwarf2-frame.c (dwarf2_frame_ops init_reg): Add "next_frame"
	argument.
	(dwarf2_frame_default_init_reg): Likewise.
	(dwarf2_frame_set_init_reg): Update init_reg arg.
	(dwarf2_frame_init_reg): Take "next_frame" and pass it to
	ops->init_reg().
	(dwarf2_frame_cache): Pass next_frame to dwarf2_frame_init_reg.
	* dwarf2-frame.h (dwarf2-frame_set_init_reg): Update declaration.
	* cris-tdep.c (cris_dwarf2_frame_init_reg): Add next_frame arg.
	* s390-tdep.c (s390_dwarf2_frame_init_reg): Likewise.
	* sh-tdep.c (sh_dwarf2_frame_init_reg): Likewise.
	* sparc64-tdep.c (sparc64_dwarf2_frame_init_reg): Likewise.
	* sparc-tdep.c (sparc32_struct_return_from_sym): New function.
	(sparc32_frame_cache): Call it.
	(sparc32_dwarf2_struct_return_p): New function.
	(sparc_dwarf2_frame_init_reg): Use it to determine if the function
	returns a structure and thus we have to indicate the return PC and
	NPC are 4 bytes later than usual.