xnest: include exevents.h for XIGetKnownProperty.

Silences compiler warning.
Pointer.c: In function ‘xnestPointerProc’:
Pointer.c:64: warning: implicit declaration of function ‘XIGetKnownProperty’
Pointer.c:64: warning: nested extern declaration of ‘XIGetKnownProperty’

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

hw/xnest/Pointer.c

@@ -34,6 +34,7 @@ is" without express or implied warranty.
 #include "Args.h"
 
 #include "xserver-properties.h"
+#include "exevents.h" /* For XIGetKnownProperty */
 
 DeviceIntPtr xnestPointerDevice = NULL;