test: Add a test for mods inside functions. Closes #493

Author: brson

src/test/run-pass/mod-inside-fn.rs

@@ -0,0 +1,11 @@
+fn f() -> int {
+    mod m {
+        fn g() -> int { 720 }
+    }
+
+    m::g()
+}
+
+fn main() {
+    assert f() == 720;
+}