cmd/compile: Go 1.22 build fails with 1.21 PGO profile on internal/saferio change [1.21 backport]

[gopherbot]

@prattmic requested issue #65615 to be considered for backport to the next 1.21 minor release.

@gopherbot Please backport to 1.21 and 1.22. This is a build failure with PGO if a hot function is changed from non-generic to generic. Only workarounds are to rename the symbol or disable PGO.

[prattmic]

I misremembered; export data lookup was only added in 1.22 (https://go.dev/cl/497175), so this bug doesn't apply to 1.21.