[clang] [llvm] [MTE] Add an attribute to opt-in memory tagging of global variables while using fsanitize=memtag-globals (#166380) (PR #182028)

[Tarcísio Fischer via cfe-commits]

tarcisiofischer wrote:

Apologies for the long delay, I wanted to check the failing test before poking anyone, and it took me a while to get back into this to try the failing test locally.

The failing test on CI is passing locally, so I _believe_ it might either be flaky or unrelated to my change. I couldn't find any other PR failing with the same issue, though. Would it be possible to re-run on CI to see if it passes, please?

Also, please let me know if there's any other concerns or comments around the implementation @pcc 

Thank you in advance!

https://github.com/llvm/llvm-project/pull/182028