tools: remove SignalFd

We don't use it anymore and it'll just be more work when
switching to async-await.

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

src/tools.rs

@@ -21,7 +21,6 @@ pub mod borrow;
 pub mod daemon;
 pub mod fs;
 pub mod futures;
-pub mod signalfd;
 pub mod ticket;
 pub mod timer;
 pub mod tty;