Package 3.31.4. Welcome meson!

Update to new version, with new soname and using meson for building and testing.

• Included some patches proposed upstream to fix some issues with meson (symbols were not hidden, wrong soname...)
• Added new build dependencies, while some are added for tests to pass (probably these should be marked differently in debian/control under a different "section", using comments)

Pkgs tested building in various archs in ubuntu at https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/3600/+packages