Fix for uninitialised bool

lib/src/upper/rlc_am.cc

@@ -914,6 +914,7 @@ void rlc_am::handle_control_pdu(uint8_t *payload, uint32_t nof_bytes)
         {
           if(!retx_queue_has_sn(i)) {
             rlc_amd_retx_t retx;
+            retx.is_segment = false;
             retx.so_start   = 0;
             retx.so_end     = it->second.buf->N_bytes;