devel/cmake-core: Drop now obsolete patch

This patch was added 16 years ago and now doesn't really make sense. There are
only a few consumers affected by this patch and it is better to fix consumers
rather than plague all FindSDL.cmake users with extra -I${LOCALBASE}

Approved by: makc (kde)
Pull Request: https://github.com/freebsd/freebsd-ports/pull/530