make: unifdef for other OSes (undefined)

*** 33,47 ****
  /*
   * 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:
--- 33,42 ----