[PATCH] libport: Move rint fallback implementations from msvcrt to libport.

[Matteo Bruni]

Perhaps unsurprisingly, I like this. Not sure that the rint* / llrint*
variants have to get the same treatment, since they are only used in
msvcrt right now. I don't think that's a bad idea though.

For what it might be worth (and, of course, no problem with
"overruling" it if necessary):

Signed-off-by: Matteo Bruni <mbruni at codeweavers.com>