XWayland GLX Path Enables sRGB Support

Another item is now crossed off the XWayland TODO list with OpenGL sRGB support wired up.

Merged this week into the XWayland GLX code is enabling of sRGB frame-buffer configurations when the underlying OpenGL driver support allows GL_FRAMEBUFFER_SRGB.

This sRGB color-space support for XWayland has long been on their TODO list but now resolved in the latest Git code for those interested. This support in turn should fix some games running on XWayland such as this bug report among likely many others out there.

The MR does note though that this change ended up breaking some OpenGL conformance test suite cases, so this change might end up being temporarily reverted depending upon what is decided, but in any case in time for the next standalone XWayland release should be all sorted out.

The remaining XWayland (GLX) TODO items are better channel mask setup and the existing bindToTextureTargets and drawable type masks code being considered suspicious.