rustc: Re-XFAIL rec-extend.rs. The typechecker never assigned the path expr a type.

src/Makefile

@@ -480,6 +480,7 @@ TEST_XFAILS_RUSTC := $(addprefix test/run-pass/, \
                         obj-return-polytypes.rs \
                         pred.rs \
                         preempt.rs \
+                        rec-extend.rs \
                         rt-circular-buffer.rs \
                         size-and-align.rs \
                         spawn-fn.rs \