Add a flag to generate the Makefile in a different directory than...

test/toplevel-dir/src/sub1/main.gyp

Index: test/toplevel-dir/src/sub1/main.gyp
===================================================================
--- test/toplevel-dir/src/sub1/main.gyp	(revision 0)
+++ test/toplevel-dir/src/sub1/main.gyp	(revision 0)
@@ -0,0 +1,18 @@
+# Copyright (c) 2009 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+{
+  'targets': [
+    {
+      'target_name': 'prog1',
+      'type': 'executable',
+      'dependencies': [
+        '<(DEPTH)/../sub2/prog2.gyp:prog2',
+      ],
+      'sources': [
+        'prog1.c',
+      ],
+    },
+  ],
+}