Also add back gssapi-keyex

While this is not currently implemented in openssh as far as I know,
there is patch floating around on the web and this may land one day
upstream.

lib/ansible/runner/connection_plugins/ssh.py

@@ -85,7 +85,7 @@ class Connection(object):
                                  "-o", "PubkeyAuthentication=no"]
         else:
             self.common_args += ["-o", "KbdInteractiveAuthentication=no",
-                                 "-o", "PreferredAuthentications=gssapi-with-mic,hostbased,publickey",
+                                 "-o", "PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey",
                                  "-o", "PasswordAuthentication=no"]
         if self.user != pwd.getpwuid(os.geteuid())[0]:
             self.common_args += ["-o", "User="+self.user]