Read longer buffer over TCP connections

Changed 'dnscache' server to read longer buffers over TCP
connections. Earlier it used to read 1 byte at a time. That is
slower, plus for long messages(ex: 65535 bytes), that means
those many read(2) calls. Thus unnecessarily burning CPU cycles.
It could also lead to potential denial of service.

   $ drill -t PTR 29.240.156.69.in-addr.arpa
   ...
   ;; MSG SIZE  rcvd: 53570

Reading longer buffers accelerates the reading, making slight
gain in performance.

Thanks to Mr Frank Denis for creating this patch and for making it
available for all.
  -> http://download.pureftpd.org/misc/dnscache-dos.c
Read tinydns data file every 5 seconds

commit 'e3e067cb9764' merged the one-second.patch. It modified
tinydns(8) server to read its data file every one second. But every
second read seems too often and unnecessary.

This patch updates that interval to 5 seconds. So the data file is
read every 5 seconds. It is still more frequent than required, but
intervals longer than it could prove troublesome to the users who
need to verify & validate changes to their data file.