We check the availability of the high precision floats in GLSL shaders which involves an OpenGL call and thus is required to be executed on the OpenGL thread. The tests were not respecting that and could fail on more strict drivers. Tests update for 675415bf2ea9ddc75ea5e5b6eae9ae942c19d6dc Fixes https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/issues/590