Patch from David Mosberger

	* config/t-libunwind: Mention unwind-c.c.
	(SHLIB_LC): Overwrite the default-value from t-slibgcc-elf-ver
	and mention -lunwind so that the resulting libgcc_s.so has
	the necessary DT_NEEDED entry for libunwind.
	* unwind-libunwind.c (_Unwind_GetCFA): Implement.
	(_Unwind_GetBSP) [UNW_TARGET_IA64]: New function.

From-SVN: r73777