Android: refactor video renderer.

Removed the overhead of having to create a shared OpenGL context in the GUI
thread and pre-render the frame into a FBO.

We now directly render the GL_TEXTURE_EXTERNAL_OES in the QtQuick render
thread, using an Android-specific QSGVideoNode.
We also use a callback from the render thread to create the texture from
there and not have to create a separate shared OpenGL context.

Change-Id: I6c8eb94b47d0a03329c912701b8af3fb5ebd1876
Reviewed-by: Christian Stromme <christian.stromme@digia.com>

src/plugins/android/videonode/videonode.pro

@@ -0,0 +1,16 @@
+TARGET = qtsgvideonode_android
+QT += quick multimedia-private qtmultimediaquicktools-private
+
+PLUGIN_TYPE = video/videonode
+PLUGIN_CLASS_NAME = QAndroidSGVideoNodeFactoryPlugin
+load(qt_plugin)
+
+HEADERS += \
+    qandroidsgvideonodeplugin.h \
+    qandroidsgvideonode.h
+
+SOURCES += \
+    qandroidsgvideonodeplugin.cpp \
+    qandroidsgvideonode.cpp
+
+OTHER_FILES += android_videonode.json