fs: Replace zero-length array with flexible-array member

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

fs/hfs/btree.h

@@ -60,7 +60,7 @@ struct hfs_bnode {
 	wait_queue_head_t lock_wq;
 	atomic_t refcnt;
 	unsigned int page_offset;
-	struct page *page[0];
+	struct page *page[];
 };
 
 #define HFS_BNODE_ERROR		0