Replace RE2 import with a dependency

third_party/re2/util/valgrind.cc

Index: third_party/re2/util/valgrind.cc
diff --git a/third_party/re2/util/valgrind.cc b/third_party/re2/util/valgrind.cc
deleted file mode 100644
index 19ec22ee1db5a2f32889d96515f579b0811d464a..0000000000000000000000000000000000000000
--- a/third_party/re2/util/valgrind.cc
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright 2009 The RE2 Authors.  All Rights Reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-#include "util/util.h"
-#ifndef _WIN32
-#include "util/valgrind.h"
-#endif
-
-namespace re2 {
-
-bool RunningOnValgrind() {
-#ifdef RUNNING_ON_VALGRIND
-  return RUNNING_ON_VALGRIND != 0;
-#else
-  return false;
-#endif
-}
-
-}  // namespace re2