ruby: disable openssl for host variant

As reported by Fatih Aşıcı on the mailing list it sometimes fails with
the host openssl depending on versions when development files are
installed.
And as suggested by Thomas Petazzoni it's really not required for
anything so just disable it.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>