[clang] [WinEH] Check object unwinding in seh block only when -eha is used (PR #180108)

[via cfe-commits]

GkvJwa wrote:

@efriedma-quic @aeubanks, Hello, can take a look at this patch, bu it would be best to modify the Chromium code and compilation options later. Currently, '/eha' is not enabled in Chromium on Windows, which causes most of the EXCEPTION-related logic to behave unexpectedly.

https://github.com/llvm/llvm-project/pull/180108