[clang] [clang-cl] [AST] Fix MS 1920+ placeholder return type mangling for lambdas (PR #105999)

[Max Winkler via cfe-commits]

MaxEW707 wrote:

> LLVM Buildbot has detected a new failure on builder `sanitizer-x86_64-linux` running on `sanitizer-buildbot1` while building `clang` at step 2 "annotate".
> 
> Full details are available at: https://lab.llvm.org/buildbot/#/builders/66/builds/3102
> Here is the relevant piece of the build log for the reference

I took a look and it appears this is a common spurious failure on this build bot.

https://github.com/llvm/llvm-project/pull/105999