Tidy logging code not using UNIMPLEMENTED.

Change-Id: I7a79c1671a6ff8b2040887133b3e0925ef9a3cfe
diff --git a/runtime/dex_file.cc b/runtime/dex_file.cc
index 78cbe58..761441e 100644
--- a/runtime/dex_file.cc
+++ b/runtime/dex_file.cc
@@ -1182,13 +1182,14 @@
   case kArray:
   case kAnnotation:
     UNIMPLEMENTED(FATAL) << ": type " << type_;
-    break;
+    UNREACHABLE();
   case kNull:
     jval_.l = NULL;
     width = 0;
     break;
   default:
     LOG(FATAL) << "Unreached";
+    UNREACHABLE();
   }
   ptr_ += width;
 }