Copy our stable attrs into a buffer; splat that 4x.
Copy our stable attrs into a buffer; splat that 4x.

This also makes it easier for a derived shader to add additional stable
attributes if desired.

ruslansennov/playn,threerings/playn,threerings/playn,threerings/playn,threerings/playn,ruslansennov/playn,ruslansennov/playn