Fix breakage from 6th Feb thread_prologue_and_epilogue_insns change:

	* sh-protos.h (sh_need_epilogue): Declare.
	* sh.c (sh_need_epilogue_known): New static variable.
	(sh_need_epilogue): New function.
	(function_epilogue): Clear need_epilogue_known.
	* sh.md (return): Split into expander / insn pattern.
	Make the expander conditional on ! sh_need_epilogue ().

From-SVN: r32136