shared: remove return value from cgit_free_commitinfo()

This return value is never used and the function always returns NULL.

Signed-off-by: John Keeping <john@keeping.me.uk>

cgit.h

@@ -343,7 +343,7 @@ extern void cgit_free_reflist_inner(struct reflist *list);
 extern int cgit_refs_cb(const char *refname, const struct object_id *oid,
 			int flags, void *cb_data);
 
-extern void *cgit_free_commitinfo(struct commitinfo *info);
+extern void cgit_free_commitinfo(struct commitinfo *info);
 
 void cgit_diff_tree_cb(struct diff_queue_struct *q,
 		       struct diff_options *options, void *data);