pretty.h: move has_non_ascii() declaration from commit.h

The function is defined in pretty.c, so this moves the declaration to
a more logical place.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diffcore-pickaxe.c

@@ -2,12 +2,12 @@
  * Copyright (C) 2005 Junio C Hamano
  * Copyright (C) 2010 Google Inc.
  */
-#include "cache.h"
+#include "git-compat-util.h"
 #include "diff.h"
 #include "diffcore.h"
 #include "xdiff-interface.h"
 #include "kwset.h"
-#include "commit.h"
+#include "pretty.h"
 #include "quote.h"
 
 typedef int (*pickaxe_fn)(mmfile_t *one, mmfile_t *two,