listings such as gas version, passed options, and time stamp.
(listing_general_info): New function.
(print_options): New function.
(print_single_option): New function.
(print_timestamp): New function.
(MAX_DATELEN): Define.
(listing_print): Add call to listing_general_info.
* listing.h (LISTING_GENERAL): Define.
(listing_print): Add new parameter.
* as.c (show_usage): Print new switch.
(parse_args): Parse new switch.
(main): Pass command line on to listing_print.
* NEWS: Mention this new feature.
* doc/as.texinfo: Document the new sub-option.
* gas/all/gas.exp: Check the performance of the -ag command line
switch.