Adds a sunxi-cedrus-drv-video libVA backend

This VA backend uses v4l2's Frame API proposal to interface with the
"sunxi-cedrus" video driver on Allwinner SoC. Only a few parts of the
code are really dependent on sunxi-cedrus and this VA backend could be
reused for other v4l drivers using the Frame API.

autogen.sh

@@ -0,0 +1,7 @@
+#! /bin/sh
+
+autoreconf -v --install
+
+if test -z "$NOCONFIGURE"; then
+    ./configure "$@"
+fi