core: parser - added vdata void* field inside msg_ldata_t structure

- useful to link to custom local data on message processing

src/core/parser/msg_parser.h

@@ -268,6 +268,7 @@ typedef struct ocd_flow {
  * - add to msg_ldata_reset() if a field uses dynamic memory */
 typedef struct msg_ldata {
 	ocd_flow_t flow;
+	void *vdata;
 } msg_ldata_t;
 
 /*! \brief The SIP message */