Remove unused setupFunc from extensions

setupFunc was used as an early callback for half-modular extensions such
as Xv, XvMC and DGA to set up hooks between the core server and the
modular component.  Now we've rid ourselves of that, we can also bin
setupFunc.

Signed-off-by: Daniel Stone <daniel@fooishbar.org>
Reviewed-by: Jamey Sharp <jamey@minilop.net>
Signed-off-by: Keith Packard <keithp@keithp.com>

include/extension.h

@@ -84,7 +84,6 @@ typedef struct {
     InitExtension initFunc;
     const char *name;
     Bool *disablePtr;
-    InitExtension setupFunc;
 } ExtensionModule;
 
 extern _X_EXPORT unsigned short StandardMinorOpcode(ClientPtr /*client */ );