MINOR: fd cache: And the thread_mask with all_threads_mask.

MINOR: fd cache: And the thread_mask with all_threads_mask.

When we choose to insert a fd in either the global or the local fd update list,
and the thread_mask against all_threads_mask before checking if it's tid_bit,
that way, if we run with nbthreads==1, we will always use the local list,
which is cheaper than the global one.