Do not start if llvmpipe software renderer is in use.

Currently plasma wayland session will hang with xwayland going into a defunct state if the software renderer (llvmpipe) is used and xwaylandvideobridge is enabled in autostart. This prevents plasma wayland session from being accessible in a VM.

This MR is a workaround that disables xwaylandvideobridge from starting if llvmpipe is detected as the renderer via glxinfo.

I don't know if this is the best way to go about this or if there is some other preferred method to get the gl renderer. I just used very basic c++ knowledge to work around the issue and added glx-utils to the package dependencies.

This does however allow xwaylandvideobridge to be shippable in ISOs/kickstarts. Without it the plasma session hangs either at the splash screen or right after it.