The segfault looks like some kind of LLVM issue on shutdown, we can probably
ignore that for now.

The real problem is that your GPU hangs even while running the trivial shaders
egltri_screen uses. Alex, could it be we're trying to use a missing/disabled
shader engine or something like that?

Hristo, can you also attach the kernel output corresponding to egltri_screen? I
expect it'll be basically the same as for starting X, but just in case.