arm: cleanup dead async code

arm/async.cc

@@ -165,31 +165,4 @@ void resume(AwaitableType type) {
     delete stuff;
 }
 
-}  // namespace async
-
-#if 0
- 
-task<buffer> readline() {
-  int size = 0;
-  char c;
- 
-  buffer buff = buffer::make(32);
- 
-//  fcntl(0, F_SETFL, fcntl(0, F_GETFL) | O_NONBLOCK);
- 
-  while (true) {
-    int n = read(0, &c, 1);
-    if (n < 1) {
-      co_await co_waitio();
-      continue;
-    }
-    buff.data[size++] = static_cast<std::byte>(c);
- 
-    if (c == '\n') {
-      buff.data = buff.data.subspan(0, size);
-      co_return buff;
-    }
-  }
-}
-
-#endif  // 0
+}  // namespace async