* normal/arg.c: Use <> instead of "" to include header files.
(SHORT_ARG_HELP): New macro.
(SHORT_ARG_USAGE): Likewise.
(help_options): Specify SHORT_ARG_HELP and SHORT_ARG_USAGE instead
of 'h' and 'u' for help and usage, respectively. Use more GNU-like
descriptions.
(find_short): Check if C is 'h' or 'u' explicitly.
(grub_arg_show_help): Use space characters instead of tabs. Treat
SHORT_ARG_HELP and SHORT_ARG_USAGE exceptionally so that -h and -u
are shown with --help and --usage only if they are not used for
the command itself.
(parse_option): Use SHORT_ARG_HELP and SHORT_ARG_USAGE instead of
'h' and 'u'.
* include/grub/arg.h (struct grub_arg_option): Add the qualifier
const into "longarg". Change the type of "shortarg" to int.