Corruption has again been reported on Intel hardware running Xorg with
the modesetting driver (which uses OpenGL based acceleration instead of
SNA acceleration the intel driver defaults to).
Reported in various forms on Sandy Bridge (X220), Ivy Bridge (X230) and
Haswell (X240). Confirmed to not occur with the intel driver but the
xserver was changed to default to the modesetting driver on >= gen4
hardware (except Ironlake).
One means of triggering this is to open a large pdf with xpdf on an
idle machine and highlight a section of the document.
There have been reports of gpu hangs on gen4 intel hardware
(T500 with GM45, X61 with 965GM) when starting Xorg as well.
require python/bison a configure flag instead of the previous way of
testing whether python was found (which shouldn't be the case in
xenocara even with ports packages installed).
This is required when timestamps change on files causing targets to be
invoked that will break if python and bison aren't available and found
in path by the configure script.
