Don't forward enter or escape to unlock window on first event

If the user presses enter or escape in order to get the unlock dialog to
show in the first place, forwarding that event to the dialog will only
cause it to close immediately.

Also took the opportunity to clean up the dependencies where I have my
own patches.  I'm now using the cargo 'patch' section so that the
dependencies specified in the individual Cargo.toml files are clean.

systemd/Cargo.toml

@@ -12,7 +12,6 @@ bscreensaver-util = { path = "../util" }
 futures = "0.3"
 log = "0.4"
 nix = "0.23"
-# git source needed until extension event error resolution fix is released
-xcb = { git = "https://github.com/rust-x-bindings/rust-xcb", rev = "d09b5f91bc07d56673f1bc0d6c7ecd72b5ff7b3e" }
+xcb = "1"
 zbus = "2.2"
 logind-zbus = "3"