When the prover is set to "any", Cryptol now checks for all available,
supported provers, submits the problem to all of them in parallel, and
uses the result from whichever finishes first.
intSize was undefined, causing repl terminate. This is probably because
the incorrect type signature using the scoped type variable (`:: a`
should probably have been `:: SBV a`) either way, bitSize and
bitSizeMaybe should use the same code when the size is finite.
