qemu-socket: set passed fd non-blocking in socket_connect()

qemu-socket: set passed fd non-blocking in socket_connect()

socket_connect() sets non-blocking on TCP or UNIX domain sockets if a
callback function is passed.  Do the same for file descriptor passing,
otherwise we could unexpectedly be using a blocking file descriptor.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 35fb94fa292173a3e1df0768433e06912a2a88e4)

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>