package/piglit: fix GL tests

Fixes:
 - http://autobuild.buildroot.org/results/3355e4dc02b07ccfd9fe9b5cafb70c01fc88c158



Add an upstream patch to ensure tests needing GLESv3 are only built when
that is available.

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>