mesa: Use glVertexAttrib*NV functions for fixed function attribs.

mesa: Use glVertexAttrib*NV functions for fixed function attribs.

In the glArrayElement implementation, use glVertexAttrib*NV type
functions for fixed function attributes. We do the same in display
execution when the list is replayed using immediate mode attribute
functions. Using a single set of function pointers enables to
use a unified loop to walk the vertex array attributes.

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