Add Mock OEMCrypto Stub

I added a Mock OEMCrypto implementation with stubs only.

I corrected the "extern C" location in OEMCrypto.h. (Thanks, Jerry!)

I added some Android.mk files that allows us to compile and
run a few simple unit tests.

Unit Test 1: The library compiles. (passes)
Unit Test 2: The test program links and runs. (passes)

Change-Id: Ib4c9554553de49645b5841b0bae889728cbfc8b1

libwvdrmengine/oemcrypto/mock/MockOEMCrypto.h

@@ -0,0 +1,22 @@
+/*********************************************************************
+ * MockOEMCrypto.h
+ *
+ * (c) Copyright 2011-2012 Google, Inc.
+ *
+ * Mock implementation of OEMCrypto.h used for testing.
+ *********************************************************************/
+
+#ifndef WV_MOCK_OEMCRYPTO_H_
+#define WV_MOCK_OEMCRYPTO_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern void initializeMockOEMCrypto();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _WV_MOCK_OEMCRYPTO_H_