Apparently find_package() and pkg_check_modules() return different
variables, while piglit still builds on my system without this patch if
fails on many other systems. This problem was doubly masked by the fact
that in the original series there is an additional patch to use waffle's
cmake config file instead of pkg_config. That patch is waiting for the
next cmake release.

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Tested-by: Mark Janes <mark.a.janes@intel.com>