cmd/compile: unnecessary internal variables are exported to DWARF for range-over-func loops

[aarzilli]

The compiler exports to DWARF a variety of internal variables (#state, #next, parameters) for range-over-func loops that exist to facilitate the implementation of range-over-func but have no value for users.
These should probably not be exported.

[gopherbot]

Change https://go.dev/cl/594257 mentions this issue: cmd/compile: drop internal range-over-func vars from DWARF output