Fix later_api.h is newer than installed later

[shikokuchuo]

This somehow errors with:

Error in .Internal(dyn.load(x, as.logical(local), as.logical(now), "")) : 
  function 'execLaterFdNative' not provided by package 'later'

after going through the steps here: #204 (comment).

@jcheng5 @wch

[jcheng5]

Well, you did better than Claude 3.5 Sonnet did--it hallucinated an R_GetErrorHandler and R_SetErrorHandler API--which would've been really cool! 😞

[shikokuchuo]

I haven't found the bug... or why yours seems to work when it's fundamentally the same structure!

[shikokuchuo]

Same error here: https://github.com/r-lib/later/actions/runs/12058747723/job/33626041239?pr=205#step:6:16
But it clearly does work in normal circumstances... there's obviously something I'm missing.

[shikokuchuo]

With the help of https://github.com/jcheng5/laterfdtest I can see now that it is working, and it's simply the error message that's being printed by R_ToplevelExec(), as Joe hinted at all along.

Porting across the helpful message dummy function, that now prints when expected, but after the first strange message. Unfortunately this seems unavoidable. To solve this we'd have to temporarily divert stderr.

[shikokuchuo]

This is superseded by the merged #204. But noting that it is possible to implement this in future - if somehow the trouble of diverting the stderr output from R_ToplevelExec() becomes the lesser evil.