Tidy logging code not using UNIMPLEMENTED.

Change-Id: I7a79c1671a6ff8b2040887133b3e0925ef9a3cfe
diff --git a/runtime/entrypoints/entrypoint_utils-inl.h b/runtime/entrypoints/entrypoint_utils-inl.h
index 9fb9a3b..ccc5d83 100644
--- a/runtime/entrypoints/entrypoint_utils-inl.h
+++ b/runtime/entrypoints/entrypoint_utils-inl.h
@@ -499,11 +499,8 @@
     case StaticPrimitiveRead:    is_primitive = true;  is_set = false; is_static = true;  break;
     case StaticPrimitiveWrite:   is_primitive = true;  is_set = true;  is_static = true;  break;
     default:
-      LOG(FATAL) << "UNREACHABLE";  // Assignment below to avoid GCC warnings.
-      is_primitive = true;
-      is_set = true;
-      is_static = true;
-      break;
+      LOG(FATAL) << "UNREACHABLE";
+      UNREACHABLE();
   }
   if (UNLIKELY(resolved_field->IsStatic() != is_static)) {
     // Incompatible class change.