kqueue: invalidate fd in uv_fs_event_t
kqueue: invalidate fd in uv_fs_event_t

Invalidate file descriptor when closing `uv_fs_event_t` handle. Note
that `uv__io_stop` is just removing `fd` from `loop->watchers` and not
actually invalidating all consequent events in a `kevent()` results.

fix joyent/node#1101

unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso