Remove mterp reliance on code item layout

Pass dex instruction pointer intead of code item pointer to the mterp
entry code. This removes a dependency on the code item layout since it
may change in the future for compact dex.

Bug: 63756964
Test: test/testrunner/testrunner.py --host -j40

Change-Id: Icfffb2e17372439f0833ecce1c0ddb05e7e7e69c
diff --git a/runtime/interpreter/interpreter.cc b/runtime/interpreter/interpreter.cc
index 038405e..01b7d4e 100644
--- a/runtime/interpreter/interpreter.cc
+++ b/runtime/interpreter/interpreter.cc
@@ -314,7 +314,10 @@
             return ExecuteSwitchImpl<false, false>(self, code_item, shadow_frame, result_register,
                                                    false);
           }
-          bool returned = ExecuteMterpImpl(self, code_item, &shadow_frame, &result_register);
+          bool returned = ExecuteMterpImpl(self,
+                                           code_item->insns_,
+                                           &shadow_frame,
+                                           &result_register);
           if (returned) {
             return result_register;
           } else {