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

build/detect_host_arch.py

Index: build/detect_host_arch.py
diff --git a/build/detect_host_arch.py b/build/detect_host_arch.py
new file mode 100755
index 0000000000000000000000000000000000000000..19579ebbc1376ad48da09bc12cc7e9a8c1e6561a
--- /dev/null
+++ b/build/detect_host_arch.py
@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+# Copyright 2014 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.
+
+"""Outputs host CPU architecture in format recognized by gyp."""
+
+import platform
+import re
+import sys
+
+
+def HostArch():
+  """Returns the host architecture with a predictable string."""
+  host_arch = platform.machine()
+
+  # Convert machine type to format recognized by gyp.
+  if re.match(r'i.86', host_arch) or host_arch == 'i86pc':
+    host_arch = 'ia32'
+  elif host_arch in ['x86_64', 'amd64']:
+    host_arch = 'x64'
+  elif host_arch.startswith('arm'):
+    host_arch = 'arm'
+
+  # platform.machine is based on running kernel. It's possible to use 64-bit
+  # kernel with 32-bit userland, e.g. to give linker slightly more memory.
+  # Distinguish between different userland bitness by querying
+  # the python binary.
+  if host_arch == 'x64' and platform.architecture()[0] == '32bit':
+    host_arch = 'ia32'
+
+  return host_arch
+
+def DoMain(_):
+  """Hook to be called from gyp without starting a separate python
+  interpreter."""
+  return HostArch()
+
+if __name__ == '__main__':
+  print DoMain([])