Linux x86_64 tests clear now

Hi all,

Similar to MacOSX, I’ve got Linux tests marked properly to skip intermittent tests (and fixed up a few) so that we should be all green on tests for now on Linux. So, please run the tests when working on Linux, and assume there’s a good chance that a pending change broke something if you see any test failures show up.

We’ll also need to fix the intermittent tests. But for now, they should no longer confuse detecting new test breakage on candidate code changes.