rs6000: New enum epilogue_type

rs6000: New enum epilogue_type

We currently call rs6000_emit_epilogue with a boolean parameter saying
if this is for a sibcall.  We also need to create epilogues for
eh_return.  This isn't yet indicated directly: instead, we get an
eh_return epilogue if crtl->calls_eh_return and this is not a sibcall.

This patch changes things so there is a three-way enum argument.

What is called "normal" now can still actually be "eh_return".  The
rs6000_emit_epilogue function still uses an "int sibcall" variable
internally.

	* config/rs6000/rs6000-protos.h (rs6000_emit_epilogue): Change
	arguments.
	* config/rs6000/rs6000.c (rs6000_emit_epilogue): Change arguments.
	* config/rs6000/rs6000.md (epilogue_type): New define_enum.
	(sibcall_epilogue): Adjust.
	(epilogue): Adjust.

From-SVN: r271184