Retab ncat-test.pl.
Round out EOF and shutdown tests.

The existing tests here didn't make much sense, and didn't cover all the
situations we care about. The 8 tests now check each of

client !--send-only EOF on stdin
client  --send-only EOF on stdin
server !--send-only EOF on stdin
server  --send-only EOF on stdin

client !--recv-only EOF on socket
client  --recv-only EOF on socket
server !--recv-only EOF on socket
server  --recv-only EOF on socket

The other thing we care about is whether the client/server keeps running
after the EOF. That is now checked in each of the tests too.
Simplify connect-mode stdin EOF handling.
Quit on socket EOF only in --recv-only mode.

Suggested by Tomas Hozza.
http://seclists.org/nmap-dev/2013/q1/188
Close stdout on socket EOF.
CHANGELOG for Ncat socket EOF change.