[SRU][L][M][U][PATCH 0/1] generate linux-lib-rust only on amd64

[Andrea Righi]

BugLink: https://bugs.launchpad.net/bugs/2020356

[Impact]

Rust is only supported by amd64 at the moment, so there is no reason to
generate linux-lib-rust packages on the other architectures.

[Test case]

Simply build the kernel, generating all the deb packages.

[Fix]

Produce linux-lib-rust only on amd64.

[Regression potential]

If Rust will be enabled on other architectures we need to remember to
undo this change, or selectively enable the packaging on the
architectures that will get the Rust support.