tevent: remove solaris port backend

tevent: remove solaris port backend

There's no way to verify changes we would have to do tevent_port.c,
as we don't have access to a solaris build machine.

So better use the poll backend instead. In performance critical code
we typically don't deal with a lot of file descriptors so the impact
should be fairly minimal.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Pavel Filipenský <pfilipen@redhat.com>
Reviewed-by: Volker Lendecke <vl@samba.org>