GN: Add an option to build against the Debian wheezy sysroot

DEPS

 # Copyright (c) 2012, 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.
 
 vars = {
   # The dart_root is the root of our sdk checkout. This is normally
   # simply sdk, but if using special gclient specs it can be different.
   "dart_root": "sdk",
 
   # We use mirrors of all github repos to guarantee reproducibility and
@@ skipping 538 matching lines @@
       "--no_resume",
       "--bucket",
       "dart-dependencies",
       "--platform=linux*",
       "--extract",
       "-s",
       Var('dart_root') + "/third_party/clang.tar.gz.sha1",
     ],
   },
   {
+    # Pull Debian wheezy sysroot for i386 Linux
+    'name': 'sysroot_i386',
+    'pattern': '.',
+    'action': ['python', 'sdk/build/linux/sysroot_scripts/install-sysroot.py',
+               '--running-as-hook', --arch', 'i386'],
+  },
+  {
+    # Pull Debian wheezy sysroot for amd64 Linux
+    'name': 'sysroot_amd64',
+    'pattern': '.',
+    'action': ['python', 'sdk/build/linux/sysroot_scripts/install-sysroot.py',
+               '--running-as-hook', '--arch', 'amd64'],
+  },
+  {
     # Pull clang if needed or requested via GYP_DEFINES.
     'name': 'gn_clang',
     'pattern': '.',
     'action': ['python', 'sdk/tools/clang/scripts/update.py', '--if-needed'],
   },
   {
     # Update the Windows toolchain if necessary.
     'name': 'win_toolchain',
     'pattern': '.',
     'action': ['python', 'sdk/build/vs_toolchain.py', 'update'],
   },
   {
     "pattern": ".",
     "action": ["python", Var("dart_root") + "/tools/generate_buildfiles.py"],
   },
 ]