Hide/Move GHC.IOPort into other-modules.

base.cabal has

90e69f779b6 (Tamar Christina        2019-06-16 21:54:23 +0100 355)         -- GHC.IOPort -- TODO: hide again after debug

I hope the debugging is done now. Sadly that change made it into many releases.

EDIT: nothing on hackage uses that module: https://hackage-search.serokell.io/?q=GHC.IOPort