Refactor: daemons: Move throttling code into libcrmcommon

The two functions used by the control daemon can be made private
functions, with their bodies guarded by HAVE_LINUX_PROCFS. The static
functions those call can move as well and remain static.

The control daemon can get rid of the guards since the throttling
functions will return defaults if procfs isn't supported, and the
callers are set up to handle that possibility.

Fix T385