Implement bvNot as a primitive in SBV backend
Implement bvNot as a primitive in SBV backend

This means a VWord input will be kept as a VWord instead of being
blasted down to bits.

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