Mesa: fix number of buffers in st_draw_vbo().

The clean-up call to pipe->set_vertex_buffers() should use the same
number of buffers as the first call.

Signed-off-by: Pekka Paalanen <pq@iki.fi>

src/mesa/state_tracker/st_draw.c

@@ -672,7 +672,7 @@ st_draw_vbo(GLcontext *ctx,
       pipe_buffer_reference(pipe->screen, &vbuffer[attr].buffer, NULL);
       assert(!vbuffer[attr].buffer);
    }
-   pipe->set_vertex_buffers(pipe, vp->num_inputs, vbuffer);
+   pipe->set_vertex_buffers(pipe, num_vbuffers, vbuffer);
 }