Test automation for compat
Context
See #712 (closed); we're not currently validating in any way that the compat extension actually works. This is problematic to test as you need artifacts from both i686 and x86_64 builds. Steam uses ldd as a test on whether the dynamic linker works, we could probably use the same.
Description
Have some kind of tests somewhere that ensure our stuff works before we publish.
Acceptance Criteria
Have higher confidence we don't break compat32.