No longer include <ctype.h>.

[isascii, ISDIGIT]: Remove definitions.

src/chgrp.c

@@ -19,7 +19,6 @@
 
 #include <config.h>
 #include <stdio.h>
-#include <ctype.h>
 #include <sys/types.h>
 #include <grp.h>
 #include <getopt.h>
@@ -27,13 +26,6 @@
 #include "version.h"
 #include "safe-lstat.h"
 
-#if !defined (isascii) || defined (STDC_HEADERS)
-#undef isascii
-#define isascii(c) 1
-#endif
-
-#define ISDIGIT(c) (isascii (c) && isdigit (c))
-
 #ifndef _POSIX_VERSION
 struct group *getgrnam ();
 #endif