Introduce intel-gpu-overlay

A realtime display of GPU activity. Note, this is just at the point of
minimum usability...

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

overlay/x11/rgb2yuv.h

@@ -0,0 +1,7 @@
+#include <X11/Xlib.h>
+#include <X11/extensions/Xvlib.h>
+#include <cairo.h>
+#include <stdint.h>
+
+void rgb2yuv_init(void);
+int rgb2yuv(cairo_surface_t *rgb, XvImage *image, uint8_t *yuv);