PR22397, BFD internal error when message locale isn't C

PR22397, BFD internal error when message locale isn't C

This adds positional parameter support to the bfd error handler,
something that was lost 2017-04-13 when _doprnt was added with commit
c08bb8dd.  The number of format args is now limited to 9, which is
sufficient for current _bfd_error_handler messages.  If someone
exceeds 9 args they get the joy of modifying this code to support more
args (shouldn't be too difficult).

	PR 22397
	* bfd.c (union _bfd_doprnt_args): New.
	(PRINT_TYPE): Add FIELD arg.  Take value from args.
	(_bfd_doprnt): Replace ap parameter with args.  Adjust all
	PRINT_TYPE invocations and reading of format args to suit.
	Move "%%" handling out of switch handling args.  Support
	positional parameters.
	(_bfd_doprnt_scan): New function.
	(error_handler_internal): Call _bfd_doprnt_scan and read args.