is_repository_shallow(): prototype fix.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/commit.h b/commit.h
index 936f8fc..491b0c4 100644
--- a/commit.h
+++ b/commit.h
@@ -110,7 +110,7 @@
 extern int register_shallow(const unsigned char *sha1);
 extern int unregister_shallow(const unsigned char *sha1);
 extern int write_shallow_commits(int fd, int use_pack_protocol);
-extern int is_repository_shallow();
+extern int is_repository_shallow(void);
 extern struct commit_list *get_shallow_commits(struct object_array *heads,
 		int depth, int shallow_flag, int not_shallow_flag);