With [1] merged, the XMonad module from core now exports mkGrabs and
setNumlockMask (now cacheNumlockMask). However, since we want
xmonad-contrib 0.17.1 to compile against xmonad 0.17.0 still, hide the
function for now and continue to use the vendored copies we have in
X.U.Grab currently. We have to ignore the dodgy-imports warning when
-fpedantic is on, but that seems like a small price to pay.
A breaking change for this is planned for 0.18.0.
[1]: https://github.com/xmonad/xmonad/pull/405
