backport a change from incall_ctrl to fix issue with the first LDU1 after an HDU being non-standard MFId causing illegal grant demands and/or grants;

src/host/p25/packet/Voice.cpp

@@ -375,6 +375,12 @@ bool Voice::process(uint8_t* data, uint32_t len)
                 }
             }
 
+            // bryanb: due to moronic reasons -- if this case happens, default the RID to something sane
+            if (srcId == 0U && !lc.isStandardMFId()) {
+                LogMessage(LOG_RF, P25_HDU_STR " ** source RID was 0 with non-standard MFId defaulting source RID, dstId = %u, mfId = $%02X", dstId, lc.getMFId());
+                srcId = WUID_FNE;
+            }
+
             // send network grant demand TDU
             if (m_p25->m_network != nullptr) {
                 if (!m_p25->m_dedicatedControl && m_p25->m_convNetGrantDemand) {