base: kevent.filter is signed
base: kevent.filter is signed

I checked both the FreeBSD and Darwin manpages; it's signed in both cases.
This was producing validation failures on OS X due to the new literal
range-check.

ezyang/ghc,sdiehl/ghc,shlevy/ghc,shlevy/ghc,ezyang/ghc,ezyang/ghc,shlevy/ghc,sdiehl/ghc,sdiehl/ghc,shlevy/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,shlevy/ghc,shlevy/ghc,ezyang/ghc,ezyang/ghc,sdiehl/ghc,shlevy/ghc,ezyang/ghc,ezyang/ghc