Add gyp-generated bspatch (used by setup.exe) and bsdiff.

third_party/bspatch/bspatch.gyp

Index: third_party/bspatch/bspatch.gyp
===================================================================
--- third_party/bspatch/bspatch.gyp	(revision 0)
+++ third_party/bspatch/bspatch.gyp	(revision 0)
@@ -0,0 +1,31 @@
+# Copyright (c) 2009 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.
+
+{
+  'includes': [
+    '../../build/common.gypi',
+  ],
+  'targets': [
+    {
+      'target_name': 'bspatch',
+      'type': '<(library)',
+      'msvs_guid': 'D7ED06E8-6138-4CE3-A906-5EF1D9C804E0',
+      'dependencies': [
+        '../lzma_sdk/lzma_sdk.gyp:lzma_sdk',
+      ],
+      'include_dirs': [
+        '.',
+      ],
+      'direct_dependent_settings': {
+        'include_dirs': [
+          '.',
+        ],
+      },
+      'sources': [
+        'mbspatch.cc',
+        'mbspatch.h',
+      ],
+    },
+  ],
+}