Fix Windows build breakage

src/libstd/generic_os.rs

@@ -79,7 +79,7 @@ fn getenv(n: str) -> option<str> {
             }
             ret option::some(str::from_bytes(v)); // UTF-8 or fail
         } else { nsize = res; }
-    }
+    };
 }
 
 #[cfg(target_os = "win32")]