dri_util: use the implemented version of __DRIimageDriverExtension

... over the one provided by the headers.

Currently both versions are identical, but that is not
guaranteed to be the case in the future.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
1 file changed