parse-options: add parse_options_concat() to concat options

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/parse-options.h b/parse-options.h
index 9429f7e..7581e93 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -187,6 +187,7 @@
 
 extern int parse_options_end(struct parse_opt_ctx_t *ctx);
 
+extern int parse_options_concat(struct option *dst, size_t, struct option *src);
 
 /*----- some often used options -----*/
 extern int parse_opt_abbrev_cb(const struct option *, const char *, int);