[Pkg-rust-maintainers] Bug#1040490: Bug#1040490: librust-cipher-dev: please provide feature block-padding

[Peter Green]

> 
> Package contains a patch to remove feature block-padding, with no DEP-3
> patch headers indicating why

I did it to get the new rust-aes into testing quicker while we wait for
either rust-block-buffer-0.9 and it's rdeps to get autoremoved from
testing, or some other resoloution that allows rust-block-padding
to migrate.

Once I get aes into testing, i'm happy to re-enable the feature.