tcpsocket.c: disable Nagle's algorithm for sent commands

tcpsocket.c: disable Nagle's algorithm for sent commands

Sent commands are very short, like "cvs co foo", "cvs co bar".
We pair them with large receive commands.
The faster we will send them out the faster we will receive
the result. Nagle's algorithm does not allow sending
requests faster, than 5 checkouts per second.

The patch speedups importing my real repository
(30 000 checkouts) from 90 minutes down to 5 minutes.

It means patch speedups from 5 checkouts to
100 checkouts per second.

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Signed-off-by: Eric S. Raymond <esr@thyrsus.com>