cmd/compile: internal compiler error invalid heap allocated var without Heapaddr [1.26 backport]

[gopherbot]

@mauri870 requested issue #80097 to be considered for backport to the next 1.26 minor release.

@gopherbot please open backport issues

[gopherbot]

Change https://go.dev/cl/800181 mentions this issue: [release-branch.go1.26] cmd/compile: don't require Heapaddr for heap vars in dead code