Xext: purge XGE event masks.

The masks were originally designed to generically handle event masks for
extensions. Since all that is in-server anyway, it's much better writing
custom event masks for those extensions that need it and not providing a
unified mechanism.
XI2 needs more than the current implementation, which is already too complex
for most other extensions. good riddance.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

include/inputstr.h

@@ -175,7 +175,6 @@ typedef struct _GrabRec {
     CursorPtr		cursor;		/* always NULL for keyboards */
     Mask		eventMask;
     Mask                deviceMask;     
-    GenericMaskPtr      genericMasks;
 } GrabRec;
 
 typedef struct _KeyClassRec {