[llvm] [Support] On Windows, fix rpmalloc TLS destructor when running inside a DLL (PR #171465)

[Alexandre Ganea via llvm-commits]

aganea wrote:

> Could you help me revise this? My English isn't very good.

No worries, I think the description is fine, I can make some changes.

> EDIT:Can we format this file once in the main branch first, and then i rebase it

If you use `git clang-format` it should only format your changes?

https://github.com/llvm/llvm-project/pull/171465