mod_net_multiplex: Add support for using ALPN Potentially a bit more efficient since it can jump to the selected protocol on connect instead of waiting for some data to look at. Adds a 'protocol' field to net providers for this purpose.

local xpcall = xpcall;

if select(2, xpcall(function (x) return x end, function () end,  "test")) ~= "test" then
	xpcall = require"util.compat".xpcall;
end

return {
	xpcall = xpcall;
};