Require render version 0.11 before using XRenderCreateSolidFill().
Apparently use of XRenderCreateSolidFill() may trigger high Xorg cpu
usage (seen on Xorg 1.7.7 with render 0.10, driver unknown).
Exact reason unknown, maybe a driver problem.
Requiring render version >= 0.11 may just be a random way to avoid
some brokenness in older Xorgs.