Merge pull request #880 from 9rnsr/2.066

Cherry-picking commits from master to 2.066 branch (for beta3)
Merge pull request #889 from MartinNowak/fix13025

fix Issue 13025 - Tools repository does not build on Ubuntu
Merge pull request #890 from klickverbot/fix-checkedint-umul

Fix issue 12958 - core.checkedint.mulu is broken.