Prevent GRUB from probing floppies during boot.
* conf/common.rmk (search_mod_CFLAGS): Use `-Werror -Wall'.
* commands/search.c (options): Add --no-floppy.
(search_fs, search_file, grub_cmd_search): Support --no-floppy.
* util/grub-mkconfig_lib.in (prepare_grub_to_access_device): Use
--no-floppy when searching for UUIDs.