openssh: Don't attempt to connect to unsupported addresses

When iterating over known addresses for the requested target host name,
skip those that are not supported by the running kernel.

MFC after: 1 week
PR: 195231
Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D53588

(cherry picked from commit 5818b6ee552b302f5300934f9b8cb94881867a5f)