KVM: 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>

include/linux/kvm_host.h

@@ -409,7 +409,7 @@ struct kvm_irq_routing_table {
 	 * Array indexed by gsi. Each entry contains list of irq chips
 	 * the gsi is connected to.
 	 */
-	struct hlist_head map[0];
+	struct hlist_head map[];
 };
 #endif