Use C11 anonymous members to make poll refs less verbose to use

union epoll_ref has a deeply nested set of structs and unions to let us
subdivide it into the various different fields we want.  This means that
referencing elements can involve an awkward long string of intermediate
fields.

Using C11 anonymous structs and unions lets us do this less clumsily.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

passt.h

@@ -60,8 +60,8 @@ union epoll_ref {
 			union udp_epoll_ref udp;
 			union icmp_epoll_ref icmp;
 			uint32_t data;
-		} p;
-	} r;
+		};
+	};
 	uint64_t u64;
 };