Add Flag for Enabling 64-bit Legacy DRM Plugins

We are ready for devices to begin migrating to a 64-bit Legacy DRM
Loader. However, not all devices are ready to make this jump yet. A
device needs to have all of its Legacy DRM Plugins ready to run as
64-bit before it can do this. This includes having 64-bit hardware
integrations.

So that devices can turn on 64-bit support as they get ready, I am
adding flags that can be set in a device's device.mk file. There are two
parts:

* ENABLE_MEDIADRM_64 enables building the Legacy DRM Plugin HAL as
  64-bit.

* Setting drm.64bit.enabled=true in PRODUCT_PROPERTY_OVERRIDES switches
  the Legacy DRM Plugin HAL to searching for DRM Plugins in the 64-bit
  directory.

Test: Validated that turning on these flags enables a 64-bit Legacy DRM
      Plugin HAL that loads 64-bit Legacy DRM Plugins from the lib64
      directory.
Bug: 36076017
Change-Id: I8d21fc7e7c0357eb6755839d41caa0f37ca20aff
diff --git a/drm/1.0/default/DrmFactory.cpp b/drm/1.0/default/DrmFactory.cpp
index 9ec0ab7..72466a1 100644
--- a/drm/1.0/default/DrmFactory.cpp
+++ b/drm/1.0/default/DrmFactory.cpp
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2016 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
@@ -17,6 +17,7 @@
 
 #include "DrmFactory.h"
 #include "DrmPlugin.h"
+#include "LegacyPluginPath.h"
 #include "TypeConvert.h"
 #include <utils/Log.h>
 
@@ -27,7 +28,7 @@
 namespace implementation {
 
     DrmFactory::DrmFactory() :
-        loader("/vendor/lib/mediadrm", "createDrmFactory") {
+        loader(getDrmPluginPath(), "createDrmFactory") {
     }
 
     // Methods from ::android::hardware::drm::V1_0::IDrmFactory follow.