Check possible undefined behavior bugs

[nightlark]

https://github.com/LLNL/TraceR/blob/master/tracer/p2p-events.C#L745

int64_t seq = 0; /* is there a better value to set if the if statement doesn't set it? */
  if(b->c7) {
    if(t->event_id == TRACER_RECV_COMP_EVT) {
      ns->my_pe->pendingRReqs[t->req_id] = t->myEntry.msgId.seq;`

• Check for undefined behavior if b->c7 is false and seq doesn't get initialized correctly (0 might not be a safe default)