vbo: Remove VBO_SAVE_PRIM_WEAK from vbo_save_NotifyBegin calls.

vbo: Remove VBO_SAVE_PRIM_WEAK from vbo_save_NotifyBegin calls.

Now looking at the implementation of vbo_save_NotifyBegin.
The VBO_SAVE_PRIM_WEAK flag, delivered in the primitive mode
argument to vbo_save_NotifyBegin, is not evaluated anymore.
The two users of the mode argument are the primitive mode
itself, where the VBO_SAVE_PRIM_WEAK bit is masked out to
retrieve the underlying OpenGL primitive mode. The other
user is to check for the VBO_SAVE_PRIM_NO_CURRENT_UPDATE bit
which is different from VBO_SAVE_PRIM_WEAK.
So, since vbo_save_NotifyBegin does not care about
VBO_SAVE_PRIM_WEAK, we can savely remove it from the call
arguments of vbo_save_NotifyBegin.

Reviewed-by: Brian Paul <brianp@vmware.com>
Signed-off-by: Mathias Fröhlich <Mathias.Froehlich@web.de>