draw/llvm: fix inputs to the geometry shader

draw/llvm: fix inputs to the geometry shader

We can't clip and viewport transform the vertices before we let
the geometry shader process them. Lets make sure the generated
vertex shader has both disabled if geometry shader is present.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: José Fonseca <jfonseca@vmware.com>