[llvm-branch-commits] [compiler-rt] [hwasan] Improve support of forking with threads (PR #75291)

[Vitaly Buka via llvm-branch-commits]

https://github.com/vitalybuka created https://github.com/llvm/llvm-project/pull/75291

Lock Lsan and Thread related date at_fork.

Clean shadow before thread starts, forked process may reuse already
mapped stack of 'lost' parent thread for new threads.