checking GL/gl.h usability... yes
checking GL/gl.h presence... yes
checking for GL/gl.h... yes
checking for X11/X.h... (cached) yes
checking whether gl x11 backend is to be built... yes


Engines:
  Software X11............: yes
  Software XCB............: no
  Software Framebuffer....: yes
  Software Qtopia.........: no
  Software Memory Buffer..: yes
  DirectFB................: no
  OpenGL X11..............: no
  Cairo X11...............: no
  XRender X11.............: yes
  XRender Xcb.............: no
  Glitz X11...............: no

$ glxinfo | grep vendor
server glx vendor string: SGI
client glx vendor string: SGI
OpenGL vendor string: Tungsten Graphics, Inc.