devPrivates rework: since API is already broken, switch everything

over to new system.

Need to update documentation and address some remaining vestiges of
old system such as CursorRec structure, fb "offman" structure, and
FontRec privates.

mi/mi.h

@@ -55,6 +55,7 @@ SOFTWARE.
 #include <X11/fonts/font.h>
 #include "input.h"
 #include "cursor.h"
+#include "privates.h"
 
 #define MiBits	CARD32
 
@@ -412,7 +413,7 @@ extern Bool miScreenInit(
     VisualPtr /*visuals*/
 );
 
-extern int miAllocateGCPrivateIndex(
+extern DevPrivateKey miAllocateGCPrivateIndex(
     void
 );