Roll Mojo to b88737ed62969ce3203085748f0d53ff4f09ba5b.

third_party/instrumented_libraries/BUILD.gn

Index: third_party/instrumented_libraries/BUILD.gn
diff --git a/testing/legion/__init__.py b/third_party/instrumented_libraries/BUILD.gn
similarity index 52%
copy from testing/legion/__init__.py
copy to third_party/instrumented_libraries/BUILD.gn
index 50b23dff631dbfd12f490f20fe2a2871179b73b9..9a25322835d5d91479d5324663513f643429f560 100644
--- a/testing/legion/__init__.py
+++ b/third_party/instrumented_libraries/BUILD.gn
@@ -1,3 +1,8 @@
 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
+
+# This is just to placate build/config/sanitizers/BUILD.gn (which we can't
+# modify, since it's pulled verbatim from upstream).
+group("deps") {
+}