Call bfd_close_all_done in ld_cleanup

This is similar to "Call bfd_close_all_done in output_file_close",
but with some code tidying in the pe/pep write_build_id functions.
write_build_id is passed the output bfd as its parameter, so there is
no need to go looking for the output bfd via link_info (and doing so
will no longer work since I clear link_info.output_bfd before calling
bfd_close).

	* emultempl/pe.em (write_build_id): Rename t to td.  Formatting.
	Don't access pe_data(link_info.output_bfd), use td instead.
	(setup_build_id): Rename t to td.  Formatting.
	* emultempl/pep.em: As for pe.em.
	* ldmain.c (ld_cleanup): Call bfd_close_all_done on linker bfds.
	(main): Clear link_info.output_bfd when closing.