Fix function `scTypeOf` on `Constant` terms.
Fix function `scTypeOf` on `Constant` terms.

Return the type directly instead of erroneously computing the
type of the type.

Fixes GaloisInc/saw-script#574.

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