Use bfd_get_filename throughout ld

	* emultempl/beos.em (sort_by_file_name): Use bfd_get_filename
	rather than accessing bfd->filename directly.
	* emultempl/pe.em (gld_${EMULATION_NAME}_after_open): Likewise.
	* emultempl/pep.em (gld_${EMULATION_NAME}_after_open): Likewise.
	* emultempl/spuelf.em (embedded_spu_file): Likewise.
	* ldlang.c (input_statement_is_archive_path, wild_sort),
	(check_excluded_libs): Likewise.
	* ldmain.c (add_archive_element): Likewise.
	* ldmisc.c (vfinfo): Likewise.
	* pe-dll.c (auto_export, generate_edata, pe_create_import_fixup),
	(pe_dll_generate_implib, pe_process_import_defs): Likewise.
	* plugin.c (plugin_object_p): Likewise.