Revert 22380 to investigate windows build break.

runtime/lib/libgen_in.cc

Index: runtime/lib/libgen_in.cc
===================================================================
--- runtime/lib/libgen_in.cc	(revision 22381)
+++ runtime/lib/libgen_in.cc	(working copy)
@@ -1,13 +0,0 @@
-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-#include "{{INCLUDE}}" // NOLINT
-
-// This file is used to generate the mapping of libraries which have
-// dart:<name> handles to the corresponding files that implement them.
-const char* {{VAR_NAME}}[] = {
-{{LIBRARY_SOURCE_MAP}}
-{{PART_SOURCE_MAP}}
-  NULL, NULL
-};