Hello,

rust-cbindgen-web build-deps on cargo-mozilla and rustc-web,
but rustc-web depends on cargo-web that conflicts with cargo-mozilla.

So, these build-deps are unresolvable. I was able to build it by
using cargo-web as build-deps instead of cargo-mozilla and by
patching cargo-web to provide cargo since its required to fulfill
dependencies of dh-cargo.

Thank you.

Best,
Dylan