[libunwind] [libunwind][test] Avoid calling back into libunwind on sanitizer errors (PR #67861)

[Alexander Richardson via cfe-commits]

arichardson wrote:

> What is the nested MSAN fault? Wouldn't fixing that be a better way to handle the situation?

Currently there are missing annotations for __unw_getcontext so MSan thinks there are unintialized reads inside libunwind. The underlying issues is fixed in #67860 but if we ever introduce an new MSan error inside libunwind we will see the same infinite recursion. 

https://github.com/llvm/llvm-project/pull/67861