Made sure that every call to bfd_read, bfd_write, and bfd_seek

	Made sure that every call to bfd_read, bfd_write, and bfd_seek
	checks the return value and handled bfd_error correctly.  These
	changes are not itemised.  Also:
	* srec.c (srec_write_record): Change return type to boolean.
	(srec_write_header): Likewise.  Also, check srec_write_record
	return value.
	(srec_write_section, srec_write_terminator): Likewise.
	(srec_write_symbols): Change return type to boolean.
	(internal_srec_write_object_contents): Check return value of
	srec_write_symbols, srec_write_header, srec_write_section, and
	srec_write_terminator.