server_queuereader: use write() instead of send()
server_queuereader: use write() instead of send()

Since we're now dealing with pipes or sockets, we can no longer use
send() which is for sockets only.  Since we don't use any special flags
anyway, always using write() is fine.

grobian/carbon-c-relay,rtoma/carbon-c-relay,Skyscanner/carbon-c-relay,zzl0/carbon-c-relay,grobian/carbon-c-relay,tjamesturner/carbon-c-relay,lyft/carbon-c-relay,lyft/carbon-c-relay,rtoma/carbon-c-relay,tjamesturner/carbon-c-relay,Skyscanner/carbon-c-relay,piotr1212/carbon-c-relay,zzl0/carbon-c-relay,piotr1212/carbon-c-relay,piotr1212/carbon-c-relay,grobian/carbon-c-relay,piotr1212/carbon-c-relay,lyft/carbon-c-relay