Add DecryptCTR to OEMCrypto Mock

This is a software only implementation of the OEMCrypto library for
testing the rest of the DRM code.  It currently implements the
OEMCrypto_DecrtyptCTR function using a clear key.

I've included the license request code so the rest of the group can
play with it, but I have only tested part of it.

This patch also has some makefiles and an integration testing.  You
should be able to generate the shared library libclearkeydrmengine.so with
cd vendor/widevine/libclearkeydrmengine; mm
You can create some unit test and integration test programs from the
directories:
vendor/widevine/libwvdrmengine/oemcrypto/test
vendor/widevine/libclearkeydrmengine/test
vendor/widevine/libclearkeydrmengine/inttest
vendor/widevine/libclearkeydrmengine/crypto/test

This change also addresses some comments about comments in OEMCryptoDASH.h
which were made in https://googleplex-android-review.googlesource.com/257323

Change-Id: Id6899b9f8d2f09e09be2ea493baa83a6b929073b

libwvdrmengine/oemcrypto/mock/Android.mk

@@ -3,18 +3,26 @@ LOCAL_PATH:= $(call my-dir)
 include $(CLEAR_VARS)
 
 
-LOCAL_SRC_FILES := MockOEMCrypto.cpp
-LOCAL_C_INCLUDES += vendor/widevine/libwvdrmengine/oemcrypto/include
+LOCAL_SRC_FILES := MockOEMCrypto.cpp \
+        OEMCryptoWrapper.cpp \
+        wvcrc.cpp \
 
-LOCAL_MODULE := libMockOEMCrypto
+LOCAL_C_INCLUDES += vendor/widevine/libwvdrmengine/oemcrypto/include \
+        external/openssl/include \
+        external/openssh
 
-LOCAL_MODULE_CLASS := SHARED_LIBRARIES
-LOCAL_MODULE_SUFFIX := .so
+LOCAL_MODULE := libmockoemcrypto
 
 LOCAL_MODULE_TAGS := tests
 
 LOCAL_SHARED_LIBRARIES := \
-    liblog \
-    libutils \
+        libstlport \
+        liblog \
+        libcorkscrew \
+        libutils \
+        libz \
+        libcutils \
+        libcrypto \
+        libdl
 
-include $(BUILD_SHARED_LIBRARY)
+include $(BUILD_STATIC_LIBRARY)