egl: Improve support for robust GLES contexts on EGL 1.5
egl: Improve support for robust GLES contexts on EGL 1.5

Allow the creation of robust GLES contexts when EGL 1.5 is available,
even when EGL_EXT_create_context_robustness is not.

Reviewed-by: Bas Nieuwenhuizen <1d31d94f30d40df7951505d1034e1e923d02ec49@basnieuwenhuizen.nl>
Reviewed-by: Emil Velikov <4c996f2f093ddd0585a556460b4cc3ba555546ef@gmail.com>
Signed-off-by: Chad Versace <a557f7f75bf28dc19ac99107f5cc7cd6b3fbdb1a@intel.com>

waffle-gl/waffle,chadversary/waffle,chadversary/waffle,waffle-gl/waffle,dcbaker/waffle,waffle-gl/waffle,chadversary/waffle,dcbaker/waffle,dcbaker/waffle,waffle-gl/waffle