Bump once_cell 1.4.0

[workingjubilee]

log had recent yanks, so bumping it.
once_cell 1.1 depended on an old version of parking_lot which depended on a (very) old version of smallvec which had recent UB fixes as noted in #75523, so bumping it. The pre-1.0 of smallvec might not have had the UB, but better to be after and certain the fix is in than before it.

And it 🎼 works on my machine~ 🎵

[rust-highfive]

r? @Mark-Simulacrum

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[workingjubilee]

Actually, sorry, sec.

[workingjubilee]

Apologies for being a three-chain morningstar flail.

[workingjubilee]

Hmm, that does not fail to build here... interesting. Oh, possibly because I'm missing a recent commit... and no. Build does not appear to work on MinGW with once_cell 1.4, but does with log 4.11, so if I come back to this I am going to try to fix that and also figure out why it's seemingly only a problem for MinGW and not myself.

[jyn514]

Is there a reason we're pulling in once_cell instead of dog-fooding #![feature(once_cell)]? Pre-existing, but seems like it could be fixed in this PR.

[Mark-Simulacrum]

We can switch to that as well, it's just somewhat harder (and dependencies are likely to remain pointing at out-of-tree once cell for some time).

I'm going to close this in favor of the more general bump PR though.