grep: use OPT_INTEGER_F for --max-depth
a91f453f64 (grep: Add --max-depth option., 2009-07-22) added the option
--max-depth, defining it using a positional struct option initializer of
type OPTION_INTEGER. It also sets defval to 1 for some reason, but that
value would only be used if the flag PARSE_OPT_OPTARG was given.
Use the macro OPT_INTEGER_F instead to standardize the definition and
specify only the necessary values. This also normalizes argh to N_("n")
as a side-effect, which is OK.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>