[PATCH xserver] tests: link against libos too

[Adam Jackson]

On Sat, 2017-01-14 at 16:27 +0500, Mihail Konev wrote:
> Thanks and sorry for late response.
> With dtrace being present, this breaks the build.
> Conditioned patch attached.

remote: I: patch #133193 updated using rev 730fd8c05f56da21894691bbd2e7ff37f67b45f4.
remote: I: 1 patch(es) updated to state Accepted.
To ssh://git.freedesktop.org/git/xorg/xserver
   704a867..730fd8c  master -> master

- ajax