dix: Rework Enter/Leave semaphore system.

Instead of a simple counter, use bits to keep track of which device is where
etc. When device enters a window (or sets focus), the bit matching the device
is set, when it leaves again, it is unset. If there are 0 bits set, then
Leave/Enter/Focus events may be sent to the client.

Same theory as before, but this should get around the insanity with
Grab/Ungrab special cases. Those cases are basically untested though.

include/windowstr.h

@@ -59,6 +59,7 @@ SOFTWARE.
 #include "miscstruct.h"
 #include <X11/Xprotostr.h>
 #include "opaque.h"
+#include "inputstr.h"
 
 #define GuaranteeNothing	0
 #define GuaranteeVisBack	1
@@ -257,11 +258,14 @@ extern ScreenSaverStuffRec savedScreenInfo[MAXSCREENS];
 extern DevPrivateKey FocusPrivatesKey;
 
 /* Used to maintain semantics of core protocol for Enter/LeaveNotifies and
- * FocusIn/Out events for multiple pointers/keyboards. 
- */ 
+ * FocusIn/Out events for multiple pointers/keyboards.
+ *
+ * Each device ID corresponds to one bit. If set, the device is in the
+ * window/has focus.
+ */
 typedef struct _FocusSemaphores {
-    int                 enterleave;
-    int                 focusinout;
+    char                enterleave[(MAX_DEVICES + 7)/8];
+    char                focusinout[(MAX_DEVICES + 7)/8];
 } FocusSemaphoresRec, *FocusSemaphoresPtr;
 
 /*