rs6000: Fix shrink-wrap-separate for AIX

rs6000: Fix shrink-wrap-separate for AIX

All out-of-line register save routines need LR, so we cannot wrap the
LR component if there are out-of-line saves.  This didn't show up for
testing on Linux because none of the tests there use out-of-line FPR
saves without also using out-of-line GPR saves, which we did handle.

This patch fixes it, and also cleans up code a little.

	* config/rs6000/rs6000.c (rs6000_get_separate_components): Do not
	make LR a separately shrink-wrapped component unless savres_strategy
	contains all of {SAVE,REST}_INLINE_{GPRS,FPRS,VRS}.  Do not wrap
	GPRs unless both {SAVE,REST}_INLINE_GPRS.  Do not disallow all
	wrapping when not both {SAVE,REST}_INLINE_GPRS.

From-SVN: r241203