[libunwind] libunwind: Remove OS requirements from tests to make them run on more OSes (PR #167642)

[Alexander Richardson via cfe-commits]

================
@@ -10,7 +10,9 @@
 // Ensure that libunwind doesn't crash on invalid info; the Linux aarch64
 // sigreturn frame check would previously attempt to access invalid memory in
 // this scenario.
-// REQUIRES: target={{(aarch64|s390x|x86_64)-.+linux.*}}
+// REQUIRES: target={{(aarch64|s390x|x86_64)-.+}}
+// UNSUPPORTED: system-windows
+// UNSUPPORTED: target={{.*-windows-gnu}}
----------------
arichardson wrote:

Looks like the `system-*` features are not set anywhere. Here is the output from one of the windows builders. I think we should just use the target regex.
```
All available features: 32-bit-pointer, buildhost=win32, buildhost=windows, c++26, can-create-symlinks, clang, clang-20, clang-20.1, clang-20.1.8, diagnose-if-support, enable-benchmarks=run, executor-has-no-bash, gcc-style-warnings, glibc-old-ru_RU-decimal-point, has-fblocks, has-fconstexpr-steps, has-no-zdump, host-has-gdb-with-python, large_tests, libcpp-has-no-experimental-hardening-observe-semantic, libcpp-has-no-experimental-syncstream, libcpp-has-no-experimental-tzdb, libcpp-has-no-incomplete-pstl, locale.en_US.UTF-8, locale.fr_CA.ISO8859-1, locale.fr_FR.UTF-8, locale.ja_JP.UTF-8, locale.ru_RU.UTF-8, locale.zh_CN.UTF-8, long_tests, objcopy-available, objective-c++, optimization=none, std-at-least-c++03, std-at-least-c++11, std-at-least-c++14, std-at-least-c++17, std-at-least-c++20, std-at-least-c++23, std-at-least-c++26, stdlib=libc++, stdlib=llvm-libc++, target=i686-w64-windows-gnu, verify-support, win32-broken-printf-a-precision, win32-broken-utf8-wchar-ctype, windows
```

https://github.com/llvm/llvm-project/pull/167642