Change generic-drop-glue.rs to be meaningful again, and un-XFAIL on rustc.

Author: graydon

src/Makefile

@@ -439,6 +439,7 @@ TEST_XFAILS_RUSTC := $(filter-out \
                         drop-on-ret.rs \
                         fact.rs \
                         generic-fn-infer.rs \
+                        generic-drop-glue.rs \
                         hello.rs \
                         int.rs \
                         i32-sub.rs \

src/test/run-pass/generic-drop-glue.rs

@@ -1,9 +1,8 @@
 fn f[T](&T t) {
-  log "dropping";
+  let T t1 = t;
 }
 
 fn main() {
-  type r = rec(@int x, @int y);
   auto x = rec(x=@10, y=@12);
-  f[r](x);
+  f(x);
 }