Fix await @ps failing with "Must specify a Promise or Channel to awai…

…t on"

21:07 < moritz> that's because .map() picks the zero-arity candidate
21:08 < moritz> iterating zero elements at a time

src/core/asyncops.pm

@@ -14,7 +14,7 @@ multi sub await(Channel:D $c) {
     $c.receive
 }
 multi sub await(*@awaitables) {
-    @awaitables.eager.map(&await)
+    @awaitables.eager.map({await $_})
 }
 
 sub cas (\val,&code) { val = code(val) } # naive implementation of cas