Fix crash in book/stencil.

Allow drivers to perform the perspective divide themselves.  Assembly
to do cliptesting without perspective divide for size-4 vectors.

src/mesa/tnl/t_context.h

@@ -1,4 +1,4 @@
-/* $Id: t_context.h,v 1.9 2001/01/05 02:26:49 keithw Exp $ */
+/* $Id: t_context.h,v 1.10 2001/01/13 05:48:26 keithw Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -412,6 +412,10 @@ typedef struct {
    GLuint DlistPrimitiveLength;
    GLuint DlistLastPrimitive;
 
+   /* Probably need a better configuration mechanism:
+    */
+   GLboolean NeedProjCoords;
+
    /* Derived state and storage for _tnl_eval_vb:
     */
    struct tnl_eval_store eval;