Move extension initialisation prototypes into extinit.h

Create extinit.h (and xf86Extensions.h, for Xorg-specific extensions) to
hold all our extension initialisation prototypes, rather than
duplicating them everywhere.

Signed-off-by: Daniel Stone <daniel@fooishbar.org>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Keith Packard <keithp@keithp.com>

render/render.c

@@ -37,6 +37,7 @@
 #include "pixmapstr.h"
 #include "colormapst.h"
 #include "extnsionst.h"
+#include "extinit.h"
 #include "servermd.h"
 #include <X11/extensions/render.h>
 #include <X11/extensions/renderproto.h>