Setting robustness with EGL fails

[elinorbgr]

Steps to reproduce:

• Modify the example window.rs by adding .with_gl_robustness(Robustness::TryRobustLoseContextOnReset) to the window builder
• Run the example under wayland or under X11 while forcing the use of EGL (by modifying platform::linux::x11::GlxOrEgl to ignore GLX for example)

The window building returns Err(OpenGlVersionNotSupported), because egl.CreateContext generated a BAD_ATTRIBUTE EGL error.

This has been reproduced one 3 computers, 2 using mesa and 1 using the nvidia proprietary drivers.

[kchibisov]

Fixed in #1435. If not reopen.