Bug#1020598: rtkit should depend on polkitd instead of policykit-1

[Christopher Martin]

Package: rtkit
Version: 0.13-4

rtkit depends on policykit-1, which is now a transitional package that
pulls in both polkitd and pkexec.

Please update rtkit to depend directly on polkitd, thereby helping
users remove pkexec.

Thanks.