meta/copy_image: use precomputed dst_internal_format to avoid segfault

If the destination is a renderbuffer, dst_tex_image will be NULL. This
fixes the *to_renderbuffer dEQP copy image tests.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
Cc: mesa-stable@lists.freedesktop.org

src/mesa/drivers/common/meta_copy_image.c

@@ -203,7 +203,7 @@ _mesa_meta_CopyImageSubData_uncompressed(struct gl_context *ctx,
          src_tex_image = wrap_renderbuffer(ctx, src_renderbuffer);
       }
       if (!make_view(ctx, src_tex_image, &src_view_tex_image, &src_view_texture,
-                     dst_tex_image->InternalFormat))
+                     dst_internal_format))
          goto cleanup;
    }