xi: More warning cleanup for input

Lots more const char stuff.

Remove duplicate defs of CoreKeyboardProc and CorePointerProc from
test/xi2/protocol-common.c

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>

include/inputstr.h

@@ -542,7 +542,7 @@ typedef struct _DeviceIntRec {
     GrabInfoRec deviceGrab;     /* grab on the device */
     int type;                   /* MASTER_POINTER, MASTER_KEYBOARD, SLAVE */
     Atom xinput_type;
-    char *name;
+    const char *name;
     int id;
     KeyClassPtr key;
     ValuatorClassPtr valuator;