Update CVC4 to the Last Release Version 1.8

[baierd]

We are currently using prerelease version 1.8 of CVC4. But 1.8 has been release as the last version of CVC4 and is roughly a year younger than our version. We should update to this latest release.

[daniel-raffler]

I've looked into this and the 2021 commit just adds a note to the README, saying that the project has been archived and is no longer maintained. The version we're using should be pretty close to the final release. Interestingly enough there are already binaries for 1.8 (final) in the SVN repository, but the rpath seems to be broken. The build script for CVC4 (ant publish-cvc4) also doesn't seem to work, but can be fixed with some minor changes. However, I then run into issues with the Java bindings as constructors for some of the generated classes are declared private. Most likely we would have to use an older version of SWIG to build this.

Should I look further into this, or can we just consider the current bindings as final?

[kfriedberger]

CVC4 is deprecated and is officially replaced by CVC5. We should minimize the human resources spent on CVC4. As long as we do not need to change the binaries, we can still support the existing version. If there are larger changes required, we can drop it completely.