i18n: i18n: diff: mark die messages for translation

While marking individual messages for translation, consolidate some
messages "option 'foo' requires a value" that is used for many
options into one by introducing a helper function to die with the
message with the option name embedded in it, and ask the translators
to localize that single message instead.

Signed-off-by: Vasco Almeida <vascomalmeida@sapo.pt>
Signed-off-by: Jean-Noel Avila <jn.avila@free.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/diff.c b/diff.c
index 534c12e..9270228 100644
--- a/diff.c
+++ b/diff.c
@@ -54,6 +54,11 @@ static char diff_colors[][COLOR_MAXLEN] = {
 	GIT_COLOR_NORMAL,	/* FUNCINFO */
 };
 
+static NORETURN void die_want_option(const char *option_name)
+{
+	die(_("option '%s' requires a value"), option_name);
+}
+
 static int parse_diff_color_slot(const char *var)
 {
 	if (!strcasecmp(var, "context") || !strcasecmp(var, "plain"))
@@ -3322,7 +3327,7 @@ void diff_setup_done(struct diff_options *options)
 	if (options->output_format & DIFF_FORMAT_NO_OUTPUT)
 		count++;
 	if (count > 1)
-		die("--name-only, --name-status, --check and -s are mutually exclusive");
+		die(_("--name-only, --name-status, --check and -s are mutually exclusive"));
 
 	/*
 	 * Most of the time we can say "there are changes"
@@ -3518,7 +3523,7 @@ static int stat_opt(struct diff_options *options, const char **av)
 			if (*arg == '=')
 				width = strtoul(arg + 1, &end, 10);
 			else if (!*arg && !av[1])
-				die("Option '--stat-width' requires a value");
+				die_want_option("--stat-width");
 			else if (!*arg) {
 				width = strtoul(av[1], &end, 10);
 				argcount = 2;
@@ -3527,7 +3532,7 @@ static int stat_opt(struct diff_options *options, const char **av)
 			if (*arg == '=')
 				name_width = strtoul(arg + 1, &end, 10);
 			else if (!*arg && !av[1])
-				die("Option '--stat-name-width' requires a value");
+				die_want_option("--stat-name-width");
 			else if (!*arg) {
 				name_width = strtoul(av[1], &end, 10);
 				argcount = 2;
@@ -3536,7 +3541,7 @@ static int stat_opt(struct diff_options *options, const char **av)
 			if (*arg == '=')
 				graph_width = strtoul(arg + 1, &end, 10);
 			else if (!*arg && !av[1])
-				die("Option '--stat-graph-width' requires a value");
+				die_want_option("--stat-graph-width");
 			else if (!*arg) {
 				graph_width = strtoul(av[1], &end, 10);
 				argcount = 2;
@@ -3545,7 +3550,7 @@ static int stat_opt(struct diff_options *options, const char **av)
 			if (*arg == '=')
 				count = strtoul(arg + 1, &end, 10);
 			else if (!*arg && !av[1])
-				die("Option '--stat-count' requires a value");
+				die_want_option("--stat-count");
 			else if (!*arg) {
 				count = strtoul(av[1], &end, 10);
 				argcount = 2;