I looked at the control file for iw and it's saying that it conflicts with aircrack-ng if the version is earlier than 1.0r2
I would guess you just have to uninstall the 1.0 version before trying to installl 1.1
Other thing it could be is that I forgot to update the version number in the changelog, and my "1.1" version is identifying itself as 1.0, but I would have been unable to install it in that case. Sorry I can't build another one at the moment, I reinstalled Windows and need to set up the build environment again.