gssapi: Add support for GSSAPIServerIdentity config option.
gssapi: Add support for GSSAPIServerIdentity config option.

mwgoldsmith/libssh,mwgoldsmith/libssh,mwgoldsmith/ssh,mwgoldsmith/ssh,mwgoldsmith/ssh,mwgoldsmith/libssh,mwgoldsmith/ssh,mwgoldsmith/libssh