diff-parseopt: convert --numstat and --shortstat

Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

diff.c

@@ -4905,6 +4905,12 @@ static void prep_parse_options(struct diff_options *options)
 			  N_("synonym for '-p --raw'"),
 			  DIFF_FORMAT_PATCH | DIFF_FORMAT_RAW,
 			  DIFF_FORMAT_NO_OUTPUT),
+		OPT_BIT_F(0, "numstat", &options->output_format,
+			  N_("machine friendly --stat"),
+			  DIFF_FORMAT_NUMSTAT, PARSE_OPT_NONEG),
+		OPT_BIT_F(0, "shortstat", &options->output_format,
+			  N_("output only the last line of --stat"),
+			  DIFF_FORMAT_SHORTSTAT, PARSE_OPT_NONEG),
 		OPT_END()
 	};
 
@@ -4933,11 +4939,7 @@ int diff_opt_parse(struct diff_options *options,
 		return ac;
 
 	/* Output format options */
-	if (!strcmp(arg, "--numstat"))
-		options->output_format |= DIFF_FORMAT_NUMSTAT;
-	else if (!strcmp(arg, "--shortstat"))
-		options->output_format |= DIFF_FORMAT_SHORTSTAT;
-	else if (skip_prefix(arg, "-X", &arg) ||
+	if (skip_prefix(arg, "-X", &arg) ||
 		 skip_to_optional_arg(arg, "--dirstat", &arg))
 		return parse_dirstat_opt(options, arg);
 	else if (!strcmp(arg, "--cumulative"))