Revert "SelfLoader: don't mix buffered and unbuffered I/O"

[tonycoz]

This reverts commit 7a6d188.

This fixed some smoke failures but introduced others, go back to the old state.

Fixes #24407

An alternative to #24409

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• This set of changes does not require a perldelta entry.

[Leont]

On the short term, this is probably the best for 5.44.

On the longer term, we should seriously consider dumping :stdio, or at the very least downgrade it to no longer being a primary layer.

[tonycoz]

On the short term, this is probably the best for 5.44.

Is that a PSC instruction? (I have no problem doing it, I just don't want (more) churn at this point.)

On the longer term, we should seriously consider dumping :stdio, or at the very least downgrade it to no longer being a primary layer.

I think it's pretty secondary now, I expect the smoking is mostly inertia - I think it's the default, but that does reveal the occasional issue.

I doubt many are using PERLIO=stdio in production.

[Leont]

Is that a PSC instruction? (I have no problem doing it, I just don't want (more) churn at this point.)

No that's my personal opinion, we haven't discussed it yet (but probably will tomorrow).