the socket interface module checks the receive.low_water_mark to automatically
notify a read event. available_data will be zero, thus enabling the notification.
fixes the test poll_nm in NSPR.
Change-Id: I5354faec439df96671506550cdb144a45f6082b1
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4820
Reviewed-by: waddlesplash <waddlesplash@gmail.com>