draw: don't pretend have_clipdist is per-vertex

draw: don't pretend have_clipdist is per-vertex

This is just for code cleanup, conceptually the have_clipdist really
isn't per-vertex state, so don't put it there (just dependent on the
shader). Even though there wasn't really any overhead associated with
this, we shouldn't store random shader information in the vertex header.

Reviewed-by: Brian Paul <brianp@vmware.com
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>