* Move configuration from lib/service to lib/service/servicecfg
The new servicecfg package will hold only configuration for services.
This will allow other packages (like tctl and tsh) to depend on
servicecfg without pulling in all of lib/service (which has a number
of platform-specific details).
This is the first step towards being able to build tctl for Windows.
* Move PAM and BPF config into servicecfg
This breaks a compile-time dependency on BPF/PAM for tctl.
Zac Bergquist