[Piglit] Patch to prefix piglit window titles with "pigli : "

[Michal Suchanek]

Hello

I was trying how managed vs unmamaged windows affect my piglit results
and wrote a patch that prefixes all piglit window titles with piglit:
to make it easier to match them in window management rules.

It seems that read-front always fails when the window is resized and
often fails when the window is managed.

Thanks

Michal