teach warn_dangling_symref to take a FILE argument

Different callers of warn_dangling_symref() may want to control whether its
output goes to stdout or stderr so let it take a FILE argument.

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-remote.c

@@ -1166,7 +1166,7 @@ static int prune_remote(const char *remote, int dry_run)
 
 		printf(" * [%s] %s\n", dry_run ? "would prune" : "pruned",
 		       abbrev_ref(refname, "refs/remotes/"));
-		warn_dangling_symref(dangling_msg, refname);
+		warn_dangling_symref(stdout, dangling_msg, refname);
 	}
 
 	free_remote_ref_states(&states);

refs.c

@@ -286,6 +286,7 @@ static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 }
 
 struct warn_if_dangling_data {
+	FILE *fp;
 	const char *refname;
 	const char *msg_fmt;
 };
@@ -304,13 +305,13 @@ static int warn_if_dangling_symref(const char *refname, const unsigned char *sha
 	if (!resolves_to || strcmp(resolves_to, d->refname))
 		return 0;
 
-	printf(d->msg_fmt, refname);
+	fprintf(d->fp, d->msg_fmt, refname);
 	return 0;
 }
 
-void warn_dangling_symref(const char *msg_fmt, const char *refname)
+void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 {
-	struct warn_if_dangling_data data = { refname, msg_fmt };
+	struct warn_if_dangling_data data = { fp, refname, msg_fmt };
 	for_each_rawref(warn_if_dangling_symref, &data);
 }
 

refs.h

@@ -29,7 +29,7 @@ extern int for_each_replace_ref(each_ref_fn, void *);
 /* can be used to learn about broken ref and symref */
 extern int for_each_rawref(each_ref_fn, void *);
 
-extern void warn_dangling_symref(const char *msg_fmt, const char *refname);
+extern void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname);
 
 /*
  * Extra refs will be listed by for_each_ref() before any actual refs