x86 selftests want a 32 bit runtime

***In GitLab by @broonie1 on Jun 6, 2022, 17:35 GMT+1:***

The x86 selftests have some coverage for 32 bit userspace which needs build support that is not provided:

```shell
Warning: you seem to have a broken 32-bit build
environment. This will reduce test coverage of 64-bit
kernels. If you are using a Debian-like distribution,
try:

apt-get install gcc-multilib libc6-i386 libc6-dev-i386

If you are using a Fedora-like distribution, try:

yum install glibc-devel.*i686

If you are using a SUSE-like distribution, try:

zypper install gcc-32bit glibc-devel-static-32bit
make[3]: Leaving directory '/build/stage/linux/tools/testing/selftests/x86'
```

*Migrated from GitLab: https://gitlab.com/Linaro/tuxmake/-/issues/189*

Start by tracing how TuxMake handles Linux x86 selftest builds and where the reported 32-bit environment warning is surfaced. Review the listed Debian, Fedora, and SUSE package requirements; done means builds provide the required 32-bit runtime so the selftests retain their 32-bit userspace coverage without the warning.

Written by the indexing model from the issue text.