Remove unused 'class cmake' members

* The `InTryCompile` member has been unused since commit 62854e99
  (cmState: Move try_compile state from cmake class., 2015-04-11,
  v3.3.0-rc1~196^2~9).

* The `ConvertMessageType` and `IsMessageTypeVisible` members have been
  unused since commit 421012a3 (cmMessenger: Extract from cmake class,
  2016-01-28, v3.7.0-rc1~222^2~1).

* The `InitializeProperties` member has been unused since commit
  de722d7d (Move property initialization to cmState., 2015-04-06,
  v3.3.0-rc1~196^2~1).

Co-Author: Vitaly Stakhovsky <vvs31415@gitlab.org>
Status Job ID Name Coverage
  External
passed ghostflow-check-master

passed ghostflow-stager

passed ghostflow-stager