Make XIGetKnownProperty take a const char * argument

Now that MakeAtom takes const char *, so can XIGetKnownProperty.
Clears 71 warnings from gcc -Wwrite-strings of the form:
devices.c:145:5: warning: passing argument 1 of 'XIGetKnownProperty' discards qualifiers from pointer target type
../include/exevents.h:128:23: note: expected 'char *' but argument is of type 'const char *'

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>

Xi/xiproperty.c

@@ -386,7 +386,7 @@ change_property(ClientPtr client, DeviceIntPtr dev, Atom property, Atom type,
  * If name is NULL, None is returned.
  */
 Atom
-XIGetKnownProperty(char *name)
+XIGetKnownProperty(const char *name)
 {
     int i;
 

include/exevents.h

@@ -126,7 +126,7 @@ extern _X_EXPORT void XIUnregisterPropertyHandler(
 );
 
 extern _X_EXPORT Atom XIGetKnownProperty(
-        char*                 name
+        const char*           name
 );
 
 extern _X_EXPORT DeviceIntPtr XIGetDevice(xEvent *ev);