[Intel-gfx] read/write ioctl usage in intel-gpu-tools, for review

[Ben Widawsky]

Here is the beginning of the port of intel-gpu-tools. It buys us enough
to not be completely broken with the 3 apps I find most important. We
badly need some kind of global arg parsing for our tools, as well as
port the rest of the tools to use INREG/OUTREG, instead of relying on
mmio, but I will save that for another day.