SDF_LOADED and its C copy in the sequencer can get out of sync

The SDF_LOADED variable and its C backing store in the sequencer can get out of sync.

The SDF_LOADED epics variable should be tracked in C by the loadedSdf character array. They can get out of sync. We read the loadedSdf variable to compute the SDF type enum (other, safe, observe). It can get to a state where the SDF_LOADED PV says 'safe' but SDF_TYPE says 0 (other/unknown). This is symptomatic of SDF_LOADED and loadedSdf not being in sync.

This was seen when the guardian did a database only load of safe_monitored.snap. LOADED_SDF said safe, but it appears that loadedSdf got safe_monitored.