wks: Do not use compression for the encrypted data.

* tools/gpg-wks-client.c (encrypt_response): Add arg -z0.
* tools/gpg-wks-server.c (encrypt_stream): Ditto.

If for example a server was built without the development packages of
the compression libraries installed, the server will not be able to
decrypt a request. In theory this can't happen due to the preference
system but it is just to easy to create the server's key using a
different version of gpg and then use gpg-wks-server built
differently.

For the short messages we exchange compression is not really required
and thus we better do without to make the system more robust.

(cherry picked from commit 70a8db0333e3c22403b3647f8b5f924f6dace719)

• Signed-off-by: Werner Koch <wk@gnupg.org>