make: unifdef for other OSes (undefined)

@@ -33,15 +33,10 @@
 /*
  * Included files
  */
 #include <mksh/i18n.h>
 #include <mksh/misc.h>          /* setup_char_semantics() */
-#if defined (linux)
-#       include <wctype.h>
-#       include <wchar.h>
-#       define wschr(x,y) wcschr(x,y)
-#endif
 
 /*
  *      get_char_semantics_value(ch)
  *
  *      Return value: