I couldn't find that particular forum post, but I did find two other places which use the patch as a way of fixing compilation on OS X (though without an explanation as to what it does.

https://gist.github.com/rkumar/547220#comment-8145
https://github.com/kelwin/ncurses-ruby/commit/e2db7a6268d213dde0158f37f6d1328c70649c40