Kqueue changelist deltas. Part 3/5. Kqueue wrapper.

Introduce simple kqueue(2) wrapper with automatic changelist management.
Connect it to build
Kqueue changelist deltas. Part 4/5. Use new wrapper

Make libinotify use new kqueue_wrapper
Kqueue changelist deltas. Part 5/5. Garbage collect.

Garbage collect old changelist management code.