selftests: x86: add 32bit build warnings for SUSE

In order to successfully build all these 32bit tests, these 32bit gcc
and glibc packages, named gcc-32bit and glibc-devel-static-32bit on SUSE,
need to be installed.

This patch added this information in warn_32bit_failure.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>