New port: math/cvc4

An efficient open-source automatic theorem prover for satisfiability modulo
theories (SMT) problems. It can be used to prove the validity (or, dually, the
satisfiability) of first-order formulas in a large number of built-in logical
theories and their combination.

WWW: https://cvc4.cs.stanford.edu/web/

PR: 227702
Submitted by: Greg V <greg@unrelenting.technology>