windows: no readiness for sockets

This is technically not good as the sockets can block the thread pool.
For now though this makes windows sort of "work".

Windows needs own backend using completition model.

src/aio/posix.zig

@@ -217,9 +217,15 @@ pub inline fn openReadiness(op: anytype) OpenReadinessError!Readiness {
             }
             break :blk .{ .fd = op.file.handle, .mode = .in };
         },
-        .accept, .recv, .recv_msg => .{ .fd = op.socket, .mode = .in },
+        .accept, .recv, .recv_msg => switch (builtin.target.os.tag) {
+            .windows => .{},
+            else => .{ .fd = op.socket, .mode = .in },
+        },
         .socket, .connect, .shutdown => .{},
-        .send, .send_msg => .{ .fd = op.socket, .mode = .out },
+        .send, .send_msg => switch (builtin.target.os.tag) {
+            .windows => .{},
+            else => .{ .fd = op.socket, .mode = .out },
+        },
         .open_at, .close_file, .close_dir, .close_socket => .{},
         .timeout, .link_timeout => .{ .fd = (try Timer.init(.monotonic)).fd, .mode = .in },
         .cancel, .rename_at, .unlink_at, .mkdir_at, .symlink_at => .{},