test_init_fn() in lib-vec.rs doesn't seem to segfault anymore. Un-XFAIL it.

Author: pcwalton

src/test/run-pass/lib-vec.rs

@@ -44,6 +44,6 @@ fn test_map() {
 
 fn main() {
   test_init_elt();
-  //XFAIL: test_init_fn();  // Segfaults.
+  test_init_fn();
   test_slice();
 }