Add pretty-printing of .debug_gnu_pubnames, .debug_gnu_pubtypes.

	Add pretty-printing of .debug_gnu_pubnames, .debug_gnu_pubtypes.
	* dwarf.c (get_gdb_index_symbol_kind_name): New function.
	(display_debug_pubnames_worker): Renamed from display_debug_pubnames.
	Add support for .debug_gnu_pubnames, .debug_gnu_pubtypes.
	(display_debug_pubnames, display_debug_pubnames_gnu): New functions.
	(display_gdb_index): Redo printing of symbol kind.
	(debug_displays): Add .debug_gnu_pubnames, .debug_gnu_pubtypes.
	* dwarf.h (dwarf_section_display_enum): Add gnu_pubnames, gnu_pubtypes.
	* readelf.c (process_section_headers): Add gnu_pubnames, gnu_pubtypes.