Only OpenGL ES 3 supports GL_TEXTURE_2D_ARRAY.

glCreateTextures is only available on OpenGL 4.5. It's not supported on
OpenGL ES.

This commit advertises the extension and adds support for
xrGetOpenGLESGraphicsRequirementsKHR

Christoph Haag authored Nov 17, 2019 and Jakob Bornecrantz committed Nov 17, 2019

Calling SDL_Init() in different threads in the same process crashes.

In this SDL2 code X11_XOpenDisplay() will be a null pointer on the second thread;

    if (SDL_X11_LoadSymbols()) {
        display = X11_XOpenDisplay(NULL);

This becomes a problem when monado starts the debug UI in a thread,
and then an OpenXR client application tries to initialize SDL.

Two consecutive SDL_Init() in the same thread is harmless though.