reduce the rust debuginfo level on selected architectures
Compiling with debuginfo=2 causes the OOM killer to interrupt the build on
launchpad builders. Initially this was only on 32 bit architectures, but with
firefox 63 it started happening frequently on arm64 and ppc64el too, and with
newer versions it started happening very frequently on s390x too.
Patch cherry-picked from Ubuntu.
Gbp-Pq: Topic fixes
Gbp-Pq: Name reduce-the-rust-debuginfo-level-on-selected-architectures.patch