i915 driver/i945 hardware: mir_demo_client_eglplasma exits immediately and silently

Improvement! With the latest vivid (Mesa 10.5), it actually works, kind of. But so slow it's pointless. This is from 1920x1200:

[1427100274.649897] perf: .mir_demo_client_eglplasma-uninstalled: 0.09 FPS, render time 10154.36ms, buffer lag 0.00ms (1 buffers)
[1427100285.094331] perf: .mir_demo_client_eglplasma-uninstalled: 0.09 FPS, render time 10443.43ms, buffer lag 0.00ms (1 buffers)
[1427100295.542456] perf: .mir_demo_client_eglplasma-uninstalled: 0.09 FPS, render time 10434.16ms, buffer lag 0.00ms (1 buffers)

You have to make the window really small to see anything that looks like actual animation:

# env MIR_CLIENT_PERF_REPORT=log bin/mir_demo_client_eglplasma -s 100x100
...
[1427100512.062754] perf: .mir_demo_client_eglplasma-uninstalled: 21.13 FPS, render time 47.01ms, buffer lag 42.27ms (2 buffers)
[1427100513.077899] perf: .mir_demo_client_eglplasma-uninstalled: 21.67 FPS, render time 45.80ms, buffer lag 46.47ms (2 buffers)
[1427100514.101317] perf: .mir_demo_client_eglplasma-uninstalled: 21.50 FPS, render time 46.19ms, buffer lag 46.83ms (2 buffers)

Confirmed fixed on both machines when upgraded to the latest vivid with Mesa 10.5.

They're hopelessly slow to run eglplasma, but they do run it.

--> bug 1583532