A file descriptor that can do multiple successful write completion
requests in a row will starve the loop because it will keep feeding
the write_completed_queue. This fix will only process items on the
write_completed_queue once per event loop (in uv__run_pending).
Any new items on the queue will be processed in the next loop.
PR-URL: https://github.com/libuv/libuv/pull/1787
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>