* mips-tdep.c (mips16_scan_prologue): Replace read_next_frame_reg

	* mips-tdep.c (mips16_scan_prologue): Replace read_next_frame_reg
	by frame_unwind_register_signed calls.
	(mips32_scan_prologue): Likewise.  Skip analysis of alloca stack
	frame allocations when called with NULL NEXT_FRAME parameter.
	(read_next_frame_reg): Remove.

	* sh-tdep.c (sh_analyze_prologue): Add FPSCR parameter.  Use it
	instead of reading the FPSCR register.
	(sh_frame_cache): Pass unwound FPSCR register value to
	sh_analyze_prologue.
	(sh_skip_prologue): Pass dummy FPSCR value to sh_analyze_prologue.

	* v850-tdep.c (v850_analyze_prologue): Add CTBP parameter.  Use it
	instead of reading the CTBP register.
	(v850_frame_cache): Pass unwound CTBP register value to
	v850_analyze_prologue.