Get rid of AIX specific PC_LOAD_SEGMENT, replace with PC_SOLIB.

	Get rid of AIX specific PC_LOAD_SEGMENT, replace with PC_SOLIB.
	* xcoffsolib.c (xcoff_solib_address):  Renamed from
	pc_load_segment_name.  Return NULL if address is not in a shared
	library.  Cleanup shared library name construction, using xasprintf.
	Format shared library member names consistent with format in exec.c.
	(solib_info):  Format shared library member names consistent with
	format in exec.c.
	* config/rs6000/nm-rs6000.h:  Replace PC_LOAD_SEGMENT with PC_SOLIB,
	using xcoff_solib_address for PC_SOLIB definition.
	* stack.c (print_frame):  Remove PC_LOAD_SEGMENT code, no longer
	needed.