drop Cancellable future in favor of abortable

futures-0.3 has a futures::future::abortable() function
which does the exact same, returns an Abortable future with
an AbortHandle providing an abort() method.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

src/tools.rs

@@ -23,7 +23,6 @@ pub mod async_io;
 pub mod borrow;
 pub mod daemon;
 pub mod fs;
-pub mod futures;
 pub mod runtime;
 pub mod ticket;
 pub mod timer;