[Release-testers] [9.0.0 Release] Release Candidate 6 is here

[Hans Wennborg via Release-testers]

Hello everyone,

9.0.0-rc6 was just tagged from the release_90 branch at r372100. In
the Git monorepo, it's tagged as llvmorg-9.0.0-rc6.

Source code and docs are available at https://prereleases.llvm.org/9.0.0/#rc6

This is the same as rc5 plus one very minor change (r371969) that
still seemed good to pick up.

I'm not allocating extra time for testing this one, expecting to tag
'final' in a day or two unless any new problem arises. If you still
have cycles to spare, testing is still very much appreciated of
course.

As usual, please file bug reports about any issues you find, marking
them blocking of https://llvm.org/PR42474

Thanks,
Hans