make: remove empty source files

@@ -62,11 +62,10 @@
 #       include <rw/xdrstrea.h>
 #       include <dmrc/dmrc.h> /* dmakerc file processing */
 #endif
 
 #include <locale.h>             /* setlocale() */
-#include <mk/copyright.h>
 #include <mk/defs.h>
 #include <mksdmsi18n/mksdmsi18n.h>      /* libmksdmsi18n_init() */
 #include <mksh/macro.h>         /* getvar() */
 #include <mksh/misc.h>          /* getmem(), setup_char_semantics() */