dix: increase default number of buttons to 10.

Currently the XTEST device is limited to the same number of buttons the core
device has. This breaks if a user has a mouse with more than 3 buttons
connected and is using a core client to fake button 8+ presses.

Rather than expecting all clients to fix themselves, just increase the
default number of buttons to 10, which is somewhat a compromise. Ideally,
the XTEST devices should adjust themselves to the highest number of buttons
available on the slave devices (like the master pointers already do), but
that's a taks for another day.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Keith Packard <keithp@keithp.com>
(cherry picked from commit 982f6648fd)

dix/devices.c

@@ -539,7 +539,7 @@ CoreKeyboardProc(DeviceIntPtr pDev, int what)
 int
 CorePointerProc(DeviceIntPtr pDev, int what)
 {
-#define NBUTTONS 7
+#define NBUTTONS 10
 #define NAXES 2
     BYTE map[NBUTTONS + 1];
     int i = 0;