libweave: Build libweave as shared library

Added own gyp files of libweave.
Added exports of necessary symbols.
Added own test runner.

CQ-DEPEND=CL:290822
BUG=brillo:1258
TEST='FEATURES=test emerge-gizmo libweave buffet'

Change-Id: I23465c676865bc1dff8d8f54bcdcb097f2894998
Reviewed-on: https://chromium-review.googlesource.com/290907
Tested-by: Vitaly Buka <vitalybuka@chromium.org>
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>
diff --git a/buffet/buffet_testrunner.cc b/buffet/buffet_testrunner.cc
new file mode 100644
index 0000000..072461d
--- /dev/null
+++ b/buffet/buffet_testrunner.cc
@@ -0,0 +1,12 @@
+// Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <base/at_exit.h>
+#include <gtest/gtest.h>
+
+int main(int argc, char** argv) {
+  base::AtExitManager exit_manager;
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}