support variadic ^:async function with await

[alexdao3]

In a variadic function, the await is transpiled into a non-async function, which is invalid javascript

(defn ^:async login-as
  "Attach email to user document and log in via custom token"
  [page uid-prefix & rest]
  (js/await 1))

compiles to

(function () {
 let f44 = function (var_args) {
let args4550 = array.call(null);
let len__22043__auto__51 = alength.call(null, arguments);
let i4652 = 0;
while(true){
if (truth_((i4652 < len__22043__auto__51))) {
args4550.push((arguments[i4652]));
let G__53 = (i4652 + 1);
i4652 = G__53;
continue;
};break;
}
;
let argseq__22205__auto__54 = ((2 < alength.call(null, args4550))) ? (new IndexedSeq(args4550.slice(2), 0, null)) : (null);
return f44.cljs$core$IFn$_invoke$arity$variadic((arguments[0]), (arguments[1]), argseq__22205__auto__54);
};
f44["cljs$core$IFn$_invoke$arity$variadic"] = function (page, uid_prefix, rest) {
return (await 1);
};
f44["cljs$lang$maxFixedArity"] = 2;
f44["cljs$lang$applyTo"] = function (seq47) {
let G__4855 = first.call(null, seq47);
let seq4756 = next.call(null, seq47);
let G__4957 = first.call(null, seq4756);
let seq4758 = next.call(null, seq4756);
let self__22052__auto__59 = this;
return self__22052__auto__59.cljs$core$IFn$_invoke$arity$variadic(G__4855, G__4957, seq4758);
};
return f44;
})

[borkdude]

Thanks! PR welcome