[Intel-gfx] drm/i915: Possible security hole in command parsing

[Rebecca N. Palmer]

Repeating those tests[1] on linux-next 20150505 gave the same results,
but having seen the intermittent "no window title bar" problem twice
more, I now have to consider it a result of my patch[0], and hence
withdraw it.

However, that doesn't mean there isn't a security problem here,
only that we need a different way to fix it.

[0] http://lists.freedesktop.org/archives/intel-gfx/2015-April/065627.html 
[1] http://lists.freedesktop.org/archives/intel-gfx/2015-May/065705.html