cmd/compile: panic during export method expression [1.17 backport]

[gopherbot]

@cuonglm requested issue #48088 to be considered for backport to the next 1.17 minor release.

@gopherbot please open a backport to go1.17

[gopherbot]

Change https://golang.org/cl/346670 mentions this issue: [release-branch.go1.17] cmd/compile: fix method expression lookup during import

[gopherbot]

Closed by merging 3969694 to release-branch.go1.17.