Remove duplicated arc_wake.rs

The auxiliary file arc_wake.rs is in run-pass/auxiliary and also
ui/async-await/auxiliary. Remove the former one as their contents
are same.
Move run-pass/futures-api.rs to ui/async-await/futures-api.rs as it
needs to use arc_wake.rs.

src/test/run-pass/auxiliary/arc_wake.rs

@@ -1,64 +0,0 @@
-// edition:2018
-
-use std::sync::Arc;
-use std::task::{
-    Waker, RawWaker, RawWakerVTable,
-};
-
-macro_rules! waker_vtable {
-    ($ty:ident) => {
-        &RawWakerVTable::new(
-            clone_arc_raw::<$ty>,
-            wake_arc_raw::<$ty>,
-            wake_by_ref_arc_raw::<$ty>,
-            drop_arc_raw::<$ty>,
-        )
-    };
-}
-
-pub trait ArcWake {
-    fn wake(self: Arc<Self>);
-
-    fn wake_by_ref(arc_self: &Arc<Self>) {
-        arc_self.clone().wake()
-    }
-
-    fn into_waker(wake: Arc<Self>) -> Waker where Self: Sized
-    {
-        let ptr = Arc::into_raw(wake) as *const ();
-
-        unsafe {
-            Waker::from_raw(RawWaker::new(ptr, waker_vtable!(Self)))
-        }
-    }
-}
-
-unsafe fn increase_refcount<T: ArcWake>(data: *const ()) {
-    // Retain Arc by creating a copy
-    let arc: Arc<T> = Arc::from_raw(data as *const T);
-    let arc_clone = arc.clone();
-    // Forget the Arcs again, so that the refcount isn't decrased
-    let _ = Arc::into_raw(arc);
-    let _ = Arc::into_raw(arc_clone);
-}
-
-unsafe fn clone_arc_raw<T: ArcWake>(data: *const ()) -> RawWaker {
-    increase_refcount::<T>(data);
-    RawWaker::new(data, waker_vtable!(T))
-}
-
-unsafe fn drop_arc_raw<T: ArcWake>(data: *const ()) {
-    // Drop Arc
-    let _: Arc<T> = Arc::from_raw(data as *const T);
-}
-
-unsafe fn wake_arc_raw<T: ArcWake>(data: *const ()) {
-    let arc: Arc<T> = Arc::from_raw(data as *const T);
-    ArcWake::wake(arc);
-}
-
-unsafe fn wake_by_ref_arc_raw<T: ArcWake>(data: *const ()) {
-    let arc: Arc<T> = Arc::from_raw(data as *const T);
-    ArcWake::wake_by_ref(&arc);
-    let _ = Arc::into_raw(arc);
-}

src/test/ui/async-await/futures-api.rs

@@ -1,3 +1,5 @@
+// run-pass
+
 // aux-build:arc_wake.rs
 
 extern crate arc_wake;