test: un-xfail now working run-pass/foreign-struct.rs, close #2334.

Author: graydon

src/test/run-pass/foreign-struct.rs

@@ -8,7 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// xfail-win32
 // Passing enums by value
 
 pub enum void { }