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);

shared.c

@@ -95,7 +95,7 @@ struct cgit_repo *cgit_get_repoinfo(const char *url)
 	return NULL;
 }
 
-void *cgit_free_commitinfo(struct commitinfo *info)
+void cgit_free_commitinfo(struct commitinfo *info)
 {
 	free(info->author);
 	free(info->author_email);
@@ -105,7 +105,6 @@ void *cgit_free_commitinfo(struct commitinfo *info)
 	free(info->msg);
 	free(info->msg_encoding);
 	free(info);
-	return NULL;
 }
 
 char *trim_end(const char *str, char c)