core: srapi - cseq update field update to be a function

srapi.h

@@ -20,6 +20,7 @@
 #define __SRAPI_H__
 
 #include "str.h"
+#include "parser/msg_parser.h"
 
 typedef void (*sr_generate_callid_f)(str*);
 
@@ -27,8 +28,9 @@ int sr_register_callid_func(sr_generate_callid_f f);
 
 sr_generate_callid_f sr_get_callid_func(void);
 
+typedef int (*sr_cseq_update_f)(sip_msg_t*);
 typedef struct sr_cfgenv {
-	int cseq_update;
+	sr_cseq_update_f cb_cseq_update;
 } sr_cfgenv_t;
 
 void sr_cfgenv_init(void);