openssh: sftp no longer needs crypto or zlib.

OpenSSH 9.1p1 removed remaining dependencies and stopped linking sftp,
sftp-server and scp against libcrypto or libz.  This change moves those
package dependencies from the default to those that still need them.
In particular, this will allow sftp-server to be installed for use with
Dropbear without needing to install zlib or openssl.

Signed-off-by: Darren Tucker <dtucker@dtucker.net>