libgcc/
	* config/rs6000/aix-unwind.h (*_REGNO): New, set of useful
	register numbers. LR_REGNO replaces R_LR.
	(ucontext_for): New, helper for ...
	(ppc_aix_fallback_frame_state): New, implementation for aix 5.2
	and 5.3 of ...
	(MD_FALLBACK_FRAME_STATE_FOR): Define for 32bit configurations.

	testsuite/
	* g++.dg/eh/sighandle.C: New testcase.

From-SVN: r187540