poll_oneoff only polled stdin for blocking fd read subscriptions,
silently dropping non-stdin pollable fds. Generalize the deferred
polling to poll each blocking fd individually, tracking remaining time
budget across iterations so total wall time never exceeds the requested
timeout.
Changes:
- Generalize poll_oneoff blocking fd handling: track each deferred
subscription's file and poll it individually instead of only stdin
- Track elapsed time per poll so N blocking fds complete within 1x
timeout
- Add test for poll_oneoff with non-stdin pollable fd
Fixes: #1500
Signed-off-by: Christian Stewart <christian@aperture.us>
Christian Stewart
5500f5c252