Comment # 1 on bug 102391 from Matt Turner

This is because the headers added in

commit 9d133dd08720d80dfc8ce098bf0972ebd05c454d
Author: Boyuan Zhang <boyuan.zhang@amd.com>
Date:   Tue Aug 15 11:33:43 2017 -0400

    tests/amdgpu: add uvd encode unit tests

were not added to the relevant _SOURCES variable, so they were not included in
the tarball by make dist.

It wasn't caught by make distcheck because of the "automagic" dependency on
cunit. The tests are silently disabled if cunit is not found.