Just remove the mesa driver from the build list. And then there should be a configure option in xorg-server to not use gl or mesa.
How do I know that my piZero does or does NOT need the gl and use framebuffer as bmarkus pointed out?
I have built the Xorg's apps,libs,xserver-1.12, what else I need to compile and the sequence so that I can bring up the GUI like piCore GUI v7?
piCore GUI is kinda customized GUI... fltk? wbar?
Thanks!