Separate libupdate_verifier module and add testcases.

Enable -Wall and expose verify_image() for testing purpose.

Test: mmma bootable/recovery
Test: recovery_component_test
Change-Id: I1ee1db2a775bafdc1112e25a1bc7194d8d6aee4f

update_verifier/update_verifier_main.cpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+// See the comments in update_verifier.cpp.
+
+#include "update_verifier/update_verifier.h"
+
+int main(int argc, char** argv) {
+  return update_verifier(argc, argv);
+}