ia64: kernel: unwind_i.h: Replace zero-length array with flexible-array

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://github.com/KSPP/linux/issues/21Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

arch/ia64/kernel/unwind_i.h

@@ -42,7 +42,7 @@ enum unw_register_index {
 
 struct unw_info_block {
 	u64 header;
-	u64 desc[0];		/* unwind descriptors */
+	u64 desc[];		/* unwind descriptors */
 	/* personality routine and language-specific data follow behind descriptors */
 };