COLUMNS and LINES environment variables

[Martti Kühne]

Hello openssh developers,

Instead of just playing nethack, I've been building a client that
would log in to nethack at alt.org and using a pipe to get the login data
from pwsafe directly onto the server.
All of this works brilliantly after playing with some stty magic (full
script in [0]), however, this way the terminal size is burned into
80x24, which is way smaller than my graphical terminal.

Anyway, I proceeded grepping some of the openssh source code and wrote
this patch [1], which I have locally tested with great success.

cheers!
mar77i

[0] https://gist.github.com/mar77i/15040d227ec9f7311f25
[1] https://gist.github.com/mar77i/673b0338a90bd53bb32e