Link sigchain to main executable

 Also export necessary symbols to preempt calls from
 libart.so

Bug: 15345057
Bug: 15426766

(cherry picked from commit 96e0cfa721925550b1cc39cdfd6084a878e6ffe2)

Change-Id: I0930d96edde7dc0636e8d50d7c778f099237f748
diff --git a/cmds/app_process/sigchain_proxy.cpp b/cmds/app_process/sigchain_proxy.cpp
new file mode 100644
index 0000000..bb7a678
--- /dev/null
+++ b/cmds/app_process/sigchain_proxy.cpp
@@ -0,0 +1,17 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "sigchainlib/sigchain.cc"