MINOR: sample/proto_tcp: export "smp_fetch_src"

This patch exports the sample fetch "smp_fetch_src()".
diff --git a/include/proto/proto_tcp.h b/include/proto/proto_tcp.h
index 056129c..d38a815 100644
--- a/include/proto/proto_tcp.h
+++ b/include/proto/proto_tcp.h
@@ -45,6 +45,9 @@
 void tcp_req_cont_keywords_register(struct tcp_action_kw_list *kw_list);
 void tcp_res_cont_keywords_register(struct tcp_action_kw_list *kw_list);
 
+/* Export some samples. */
+int smp_fetch_src(const struct arg *args, struct sample *smp, const char *kw, void *private);
+
 /* Converts the INET/INET6 source address to a stick_table key usable for table
  * lookups. <type> can be STKTABLE_TYPE_IP or STKTABLE_TYPE_IPV6. The function
  * try to convert the incoming IP to the type expected by the sticktable.
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index 00c308a..077bc13 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -1990,8 +1990,7 @@
 /************************************************************************/
 
 /* fetch the connection's source IPv4/IPv6 address */
-static int
-smp_fetch_src(const struct arg *args, struct sample *smp, const char *kw, void *private)
+int smp_fetch_src(const struct arg *args, struct sample *smp, const char *kw, void *private)
 {
 	struct connection *cli_conn = objt_conn(smp->sess->origin);