Revert "R600: Truncate and extend when packing vectors."

This reverts commit f06425c27bee4092dfdf266c36ef717b5281cb6c.
XXX - Accept anyextloads for R600 CB loads.

This breaks a few tests.

Once again the BFE seems to be causing problems preventing
other folding from going on.
R600: Add BFI intrinsic to help with writing tests.
R600: Add dag combines for BFE and BFI.

This doesn't accomplish what I was hoping yet.
R600: Move BFE to selection.

This sohuld help some foldings of sext_in_reg.
Currently breaks R600.
XXX random bfi intrinsic tests