[PATCH] show-diff.c: do not include unused header file

This is my bad.  I added #include <ctype.h> to the file,
which I ended up not using and failed to remove it.
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

show-diff.c

@@ -4,7 +4,6 @@
  * Copyright (C) Linus Torvalds, 2005
  */
 #include "cache.h"
-#include <ctype.h>
 
 static char *diff_cmd = "diff -L '%s' -u -N  - '%s'";