MINOR: global: export many symbols.

The functions "val_payload_lv" and "val_hdr" are useful with
lua. The lua automatic binding for sample fetchs needs to
compare check functions.

The "arg_type_names" permit to display error messages.
diff --git a/include/proto/arg.h b/include/proto/arg.h
index e051de5..91c1acd 100644
--- a/include/proto/arg.h
+++ b/include/proto/arg.h
@@ -48,6 +48,9 @@
 #define ARG5(m, t1, t2, t3, t4, t5) \
 	(ARG4(m, t1, t2, t3, t4) + (ARGT_##t5 << (ARGM_BITS + ARGT_BITS * 4)))
 
+/* Mapping between argument number and literal description. */
+extern const char *arg_type_names[];
+
 /* This dummy arg list may be used by default when no arg is found, it helps
  * parsers by removing pointer checks.
  */
diff --git a/include/proto/payload.h b/include/proto/payload.h
index 4b658d4..fd89c88 100644
--- a/include/proto/payload.h
+++ b/include/proto/payload.h
@@ -27,6 +27,7 @@
 #include <types/session.h>
 
 int fetch_rdp_cookie_name(struct session *s, struct sample *smp, const char *cname, int clen);
+int val_payload_lv(struct arg *arg, char **err_msg);
 
 #endif /* _PROTO_PROTO_PAYLOAD_H */
 
diff --git a/include/proto/proto_http.h b/include/proto/proto_http.h
index 579a6cb..9e99ba1 100644
--- a/include/proto/proto_http.h
+++ b/include/proto/proto_http.h
@@ -131,6 +131,7 @@
 
 struct http_req_action_kw *action_http_req_custom(const char *kw);
 struct http_res_action_kw *action_http_res_custom(const char *kw);
+int val_hdr(struct arg *arg, char **err_msg);
 
 static inline void http_req_keywords_register(struct http_req_action_kw_list *kw_list)
 {