Get rid of pblend packet op.

There was only a single code path left in TensorEvaluator using pblend. We can replace that with a call to the more general TernarySelectOp and get rid of pblend entirely from Core.

Closes #2998

See merge request libeigen/eigen!2056

Co-authored-by: Rasmus Munk Larsen <rmlarsen@google.com>
17 files changed