[clang] [WinEH] Fix crash, object unwinding in the except block (PR #172287)

[via cfe-commits]

github-actions[bot] wrote:

<!--PREMERGE ADVISOR COMMENT: Windows-->
# :window: Windows x64 Test Results

* 51560 tests passed
* 877 tests skipped
* 1 test failed

## Failed Tests
(click on a test name to see its output)

### Clang
<details>
<summary>Clang.SemaCXX/__try.cpp</summary>

```
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
c:\_work\llvm-project\llvm-project\build\bin\clang.exe -cc1 -internal-isystem C:\_work\llvm-project\llvm-project\build\lib\clang\22\include -nostdsysteminc -triple x86_64-windows -fsyntax-only -verify -fborland-extensions -fcxx-exceptions C:\_work\llvm-project\llvm-project\clang\test\SemaCXX\__try.cpp
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\clang.exe' -cc1 -internal-isystem 'C:\_work\llvm-project\llvm-project\build\lib\clang\22\include' -nostdsysteminc -triple x86_64-windows -fsyntax-only -verify -fborland-extensions -fcxx-exceptions 'C:\_work\llvm-project\llvm-project\clang\test\SemaCXX\__try.cpp'
# .---command stderr------------
# | error: 'expected-error' diagnostics seen but not expected: 
# |   File C:\_work\llvm-project\llvm-project\clang\test\SemaCXX\__try.cpp Line 42: cannot use SEH '__try' in blocks, captured regions, or Obj-C method decls
# | 1 error generated.
# `-----------------------------
# error: command failed with exit status: 1

--

```
</details>

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the `infrastructure` label.

https://github.com/llvm/llvm-project/pull/172287