Android: Add usage statistics to android.

Added an option in General config to enable/disable usage statistics. Added a popup on first open if
the user would like to engage in reporting. Clicking cancel or out of the box opts out. Only
clicking 'Ok' will enable reporting. Also added a new android specific values to report.

Source/Core/Common/AndroidAnalytics.h

@@ -0,0 +1,26 @@
+// Copyright 2018 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+#pragma once
+
+#include <functional>
+#include <string>
+
+#include "Common/Analytics.h"
+
+namespace Common
+{
+void AndroidSetReportHandler(std::function<void(std::string, std::string)> function);
+
+class AndroidAnalyticsBackend : public AnalyticsReportingBackend
+{
+public:
+  explicit AndroidAnalyticsBackend(const std::string endpoint);
+
+  ~AndroidAnalyticsBackend() override;
+  void Send(std::string report) override;
+
+private:
+  std::string m_endpoint;
+};
+}  // namespace Common