Use (void) instead of () for functions without args (Thanks fernandotcl)

See also:
http://article.gmane.org/gmane.linux.kernel/1268792

The C compiler will handle (void) as "no arguments" and () as "variadic
function" (equivalent to (...)) which might lead to subtle errors, such
as the one which was fixed with commit 0ea64ae4.

include/config.h

@@ -277,7 +277,7 @@ void load_configuration(xcb_connection_t *conn, const char *override_configfile,
  * Translates keysymbols to keycodes for all bindings which use keysyms.
  *
  */
-void translate_keysyms();
+void translate_keysyms(void);
 
 /**
  * Ungrabs all keys, to be called before re-grabbing the keys because of a