Add tests for moving nullary functions

I believe this was fixed by marijn recently.

Closes #922

src/test/run-pass/move-nullary-fn.rs

@@ -0,0 +1,8 @@
+// Issue #922
+fn f2(-thing: fn()) { }
+
+fn f(-thing: fn()) { f2(thing); }
+
+fn main() {
+    f(fn(){});
+}

src/test/run-pass/task-comm-17.rs

@@ -0,0 +1,11 @@
+// Issue #922
+
+use std;
+import std::task;
+
+fn f() {
+}
+
+fn main() {
+    task::spawn(bind f());
+}