runtime,cmd/compile: apparent memory corruption in compress/flate [1.18 backport]

[cherrymui]

Consider backporting for #54596.

This may cause (rare) GC crashes or memory corruptions. The large object case is new for Go 1.20, but it could still happen with small objects in previous releases. Thanks.

[gopherbot]

Change https://go.dev/cl/453255 mentions this issue: [release-branch.go1.18] runtime: make GC see object as allocated after it is initialized

[gopherbot]

Closed by merging 3115ed2 to release-branch.go1.18.