SVE2.2 introduces instructions with predicated forms with zeroing of
the inactive lanes. This allows in some cases to save a `movprfx` or
a `mov` instruction when emitting code for `_x` or `_z` variants of
intrinsics.
This patch adds support for emitting the zeroing forms of certain
`CLS`, `CLZ`, `CNT`, `CNOT`, and `NOT` instructions.
4b73f6a548