i965: Move brw_vs_prog_data::outputs_written into VUE map.
Future patches will allow for there to be separate VUE maps when both
a geometry shader and a vertex shader are in use. When this happens,
we will want to have correspondingly separate outputs_written
bitfields. Moving outputs_written into the VUE map will make this
easy.
For consistency with the terminology used in the VUE map, the bitfield
is renamed to "slots_valid" in the process.
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>