Add a script that can build a single voice engine library

It's a basically a copy of existing merged_lib.gpy but changed the dependency
to voice engine.

BUG=None
TEST=Local build 
Review URL: https://webrtc-codereview.appspot.com/762010

git-svn-id: http://webrtc.googlecode.com/svn/trunk@2707 4adac7df-926f-26a2-2b94-8c16560cd09d

src/build/merge_voice_libs.gyp

@@ -0,0 +1,43 @@
+# Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+{
+  'includes': [ 'common.gypi', ],
+  'targets': [
+    {
+      'target_name': 'no_op',
+      'type': 'executable',
+      'dependencies': [
+        '../voice_engine/voice_engine.gyp:voice_engine_core',
+      ],
+      'sources': [ 'no_op.cc', ],
+    },
+    {
+      'target_name': 'merge_voice_libs',
+      'type': 'none',
+      'dependencies': [
+        'no_op',
+      ],
+      'actions': [
+        {
+          'variables': {
+            'output_lib_name': 'webrtc_voice',
+            'output_lib': '<(PRODUCT_DIR)/<(STATIC_LIB_PREFIX)<(output_lib_name)<(STATIC_LIB_SUFFIX)',
+          },
+          'action_name': 'merge_libs',
+          'inputs': ['<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)no_op<(EXECUTABLE_SUFFIX)'],
+          'outputs': ['<(output_lib)'],
+          'action': ['python',
+                     'merge_libs.py',
+                     '<(PRODUCT_DIR)',
+                     '<(output_lib)',],
+        },
+      ],
+    },
+  ],
+}