cmd/compile: memory corruption when setting outer values in functional iterators [1.23 backport]

[gopherbot]

@randall77 requested issue #70035 to be considered for backport to the next 1.23 minor release.

Probably.
@gopherbot Please open a backport issue to 1.23.

This causes a serious miscompilation in certain range-over-func situations.

[gopherbot]

Change https://go.dev/cl/625535 mentions this issue: [release-branch.go1.23] cmd/compile: use a non-fragile test for "does f contain closure c?"

[gopherbot]

Closed by merging CL 625535 (commit 3726f07) to release-branch.go1.23.