fmu:Use Compile time & run time Safety switch control

   Platforms that provide HW versioning tend to have
   more FLASH and can have a PX4IO as an option.
   (E.G.) FMUv5. This change provides run time
   decision to control the safety switch on
   platfors that have BOARD_HAS_VERSIONING.

   On platforms with no versioning and have
   BOARD_HAS_STATIC_MANIFEST defined as a 1
   The decision is compile time only. When a PX4IO
   is present the fmu control of the safety is
   not built.