sipcapture: declare extern heptime in hep.c and init it to null

src/modules/sipcapture/hep.c

@@ -37,7 +37,7 @@
 
 static int count = 0;
 
-struct hep_timeinfo *heptime;
+extern struct hep_timeinfo *heptime;
 
 /* HEPv2 HEPv3 */
 int hepv2_received(char *buf, unsigned int len, struct receive_info *ri);

src/modules/sipcapture/sipcapture.c

@@ -294,7 +294,7 @@ enum hash_source source = hs_error;
 
 //unsigned int rr_idx = 0;
 
-struct hep_timeinfo *heptime;
+struct hep_timeinfo *heptime = NULL;
 
 /*! \brief
  * Exported functions