If we run out of network buffers and cannot send data, and if
we have a blocking socket, then wait until new buffers are
available before returning. As this might lead to deadlock,
wait only max 10 seconds and return ENOMEM if we cannot get
buffers in a reasonable amount of time.
Fixes#28216
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>