Skip the stack tests on Windows.

As Windows uses the native fiber implementation, the stack tests should be
ignored on Windows as the implementation intentionally errors when handing out
stacks.

crates/runtime/src/instance/allocator/pooling.rs

@@ -1557,7 +1557,7 @@ mod test {
         Ok(())
     }
 
-    #[cfg(target_pointer_width = "64")]
+    #[cfg(all(unix, target_pointer_width = "64"))]
     #[test]
     fn test_stack_pool() -> Result<(), String> {
         let pool = StackPool::new(
@@ -1680,7 +1680,7 @@ mod test {
     }
 
     #[cfg_attr(target_arch = "aarch64", ignore)] // https://github.com/bytecodealliance/wasmtime/pull/2518#issuecomment-747280133
-    #[cfg(unix)]
+    #[cfg(all(unix, target_pointer_width = "64"))]
     #[test]
     fn test_stack_zeroed() -> Result<(), String> {
         let allocator = PoolingInstanceAllocator::new(