llvmpipe: assign context's frag shader pointer before using it

The call to draw_bind_fragment_shader() was using the old fragment
shader.  This bug would have really only effected the draw module's
use of the fragment shader in the wide point stage.

src/gallium/drivers/llvmpipe/lp_state_fs.c

@@ -1062,11 +1062,11 @@ llvmpipe_bind_fs_state(struct pipe_context *pipe, void *fs)
 
    draw_flush(llvmpipe->draw);
 
+   llvmpipe->fs = fs;
+
    draw_bind_fragment_shader(llvmpipe->draw,
                              (llvmpipe->fs ? llvmpipe->fs->draw_data : NULL));
 
-   llvmpipe->fs = fs;
-
    llvmpipe->dirty |= LP_NEW_FS;
 }