cmd/link: unexpected trampoline when cross-compiling to ppc64le [1.15 backport]

[gopherbot]

@pmur requested issue #45564 to be considered for backport to the next 1.15 minor release.

@gopherbot please consider a backport to 1.16. This seems to a be a regression from go 1.16.1 to 1.16.2.

I don't think a backport to earlier versions is necessary since the issue likely affects all 1.15 releases. It might be possible to workaround by not disabling cgo, or using external linking.

[ianlancetaylor]

The backport was only requested for 1.16.