* clutter/cogl/gl/cogl-defines.h.in:
* clutter/cogl/gl/cogl-context.h:
* clutter/cogl/common/cogl-mesh.c: Rename the glBufferDataSub
function to glBufferSubData. When calling glXGetProcAddress with
the former Mesa returns a stub dispatch function which will
segfault if you try to use it. With NVIDIA it returns NULL so
_cogl_features_init decides the card doesn't have VBO support.