getport: Restore historical TCP connect timeout error code

The latest versions of mount.nfs appear not to fall back to
UDP if TCP isn't available on the server.

Our new nfs_getport() implementation is missing a bit of logic
from the original mount getport() implementation.  Without it,
nfs_probe_port() sees a TCP connect timeout as a permanent error,
so it fails immediately instead of attempting to try again with
UDP.

Similar changes for our new ping API (see the old clnt_ping()
function, which is still in utils/mount/network.c).

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>