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

[Alexander Richardson via cfe-commits]

================
@@ -6,7 +6,8 @@
 #
 #===------------------------------------------------------------------------===#
 
-# REQUIRES: target={{x86_64-.+-linux-gnu}}
+# REQUIRES: target-x86_64
+# UNSUPPORTED: system-windows
----------------
arichardson wrote:

```suggestion
# REQUIRES: target={{x86_64-.+}}
# UNSUPPORTED: target={{.*-windows.*}}
```

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