Remove IOPort#

The following GHC.Exts exports should be removed (no deprecation period):

data IOPort# s a
newIOPort# :: State# s -> (# State# s, IOPort# s o #)
readIOPort# :: IOPort# s o -> State# s -> (# State# s, o #)
writeIOPort# :: IOPort# s o -> o -> State# s -> (# State# s, Int# #)

CLC approval: https://github.com/haskell/core-libraries-committee/issues/213

Draft MR: !8776

changed milestone to %9.12.1

added Pnormal Ttask deprecation needs triage labels

removed needs triage label

assigned to @alt-romes

This seems to be more sensitive than I initially anticipated. We shouldn't do this in rush before 9.12. Let's try again for 9.14. The PR is left at !8776

changed milestone to %9.14.1

unassigned @alt-romes

@bgamari What is the status of this? Why has it not been merged yet? 9.12 is already branched from master, so what is keeping it from being merged to master?

It's a patch that requires a non-trivial rebase and then demands validation. I tried this on Monday but unfortunately found that there were unrelated WinIO issues which need to be addressed before this change can be merged (see #25838 (closed)).

assigned to @bgamari