Rewrite `setupPrestateConditions` to avoid var/global special cases.
Rewrite `setupPrestateConditions` to avoid var/global special cases.

This should make it simpler to add get-element-ptr functionality for
SetupValues.

GaloisInc/saw-script,GaloisInc/saw-script,GaloisInc/saw-script,GaloisInc/saw-script,GaloisInc/saw-script