add, update-index: fix --chmod argument help

Don't translate the argument specification for --chmod; "+x" and "-x"
are the literal strings that the commands accept.

Separate alternatives using a pipe character instead of a slash, for
consistency.

Use the flag PARSE_OPT_LITERAL_ARGHELP to prevent parseopt from adding a
pair of angular brackets around the argument help string, as that would
wrongly indicate that users need to replace the literal strings with
some kind of value.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/add.c

@@ -306,7 +306,9 @@ static struct option builtin_add_options[] = {
 	OPT_BOOL( 0 , "refresh", &refresh_only, N_("don't add, only refresh the index")),
 	OPT_BOOL( 0 , "ignore-errors", &ignore_add_errors, N_("just skip files which cannot be added because of errors")),
 	OPT_BOOL( 0 , "ignore-missing", &ignore_missing, N_("check if - even missing - files are ignored in dry run")),
-	OPT_STRING( 0 , "chmod", &chmod_arg, N_("(+/-)x"), N_("override the executable bit of the listed files")),
+	{ OPTION_STRING, 0, "chmod", &chmod_arg, "(+|-)x",
+	  N_("override the executable bit of the listed files"),
+	  PARSE_OPT_LITERAL_ARGHELP },
 	OPT_HIDDEN_BOOL(0, "warn-embedded-repo", &warn_on_embedded_repo,
 			N_("warn when adding an embedded repository")),
 	OPT_END(),

builtin/update-index.c

@@ -970,7 +970,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 			PARSE_OPT_NOARG | /* disallow --cacheinfo=<mode> form */
 			PARSE_OPT_NONEG | PARSE_OPT_LITERAL_ARGHELP,
 			(parse_opt_cb *) cacheinfo_callback},
-		{OPTION_CALLBACK, 0, "chmod", &set_executable_bit, N_("(+/-)x"),
+		{OPTION_CALLBACK, 0, "chmod", &set_executable_bit, "(+|-)x",
 			N_("override the executable bit of the listed files"),
 			PARSE_OPT_NONEG | PARSE_OPT_LITERAL_ARGHELP,
 			chmod_callback},