[release-branch.go1.19] cmd/compile: on PPC64, fix sign/zero extension when masking

[release-branch.go1.19] cmd/compile: on PPC64, fix sign/zero extension when masking

This backport required manual cleanup as go1.20 combined the
ANDCCconst and ANDconst opcodes into one. Similarly, CL 456736
introduced a suble bug by using (Select1 (ANDCCconst ...)). This
usually worked because the same rule quietly changes the type
of the newly created ANDCCconst to a tuple. This change exposed
the bug, so fix it too.

(ANDconst [y] (MOV.*reg x)) should only be merged when zero
extending. Otherwise, sign bits are lost on negative values.

(ANDconst [0xFF] (MOVBreg x)) should be simplified to a zero
extension of x. Likewise for the MOVHreg variant.

Fixes #61319

Change-Id: I04e4fd7dc6a826e870681f37506620d48393698b
Reviewed-on: https://go-review.googlesource.com/c/go/+/508775
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Paul Murphy <murp@ibm.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/509018
Auto-Submit: Heschi Kreinick <heschi@google.com>
TryBot-Bypass: Heschi Kreinick <heschi@google.com>