Change slot_mem_ctrl to classify vec[state] as GC mem. Breaking / XFAILing mutable-vec-drop.rs test.

Author: graydon

src/Makefile

@@ -321,6 +321,7 @@ TEST_XFAILS_X86 :=  test/run-pass/mlist-cycle.rs \
                     test/run-pass/vec-slice.rs \
                     test/run-pass/generic-fn-infer.rs \
                     test/run-pass/generic-recursive-tag.rs \
+                    test/run-pass/mutable-vec-drop.rs \
                     test/run-pass/bind-obj-ctor.rs \
                     test/run-pass/task-comm.rs \
                     test/compile-fail/rec-missing-fields.rs \

src/boot/me/transutil.ml

@@ -118,8 +118,11 @@ let slot_mem_ctrl (slot:Ast.slot) : mem_ctrl =
         Ast.TY_port _
       | Ast.TY_chan _
       | Ast.TY_task
-      | Ast.TY_vec _
       | Ast.TY_str -> MEM_rc_opaque
+      | Ast.TY_vec _ ->
+          if type_has_state ty
+          then MEM_gc
+          else MEM_rc_opaque
       | _ ->
           match slot.Ast.slot_mode with
               Ast.MODE_exterior _ when type_is_structured ty ->