<chrono>: optimize chrono::steady_clock::now()

[fsb4000]

Closes #2085

[randomascii]

Looks good. Land it!

[fsb4000]

Sorry, I forgot about: https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-3-c4640?view=msvc-160

It's not a big deal. Without static it works with almost same speed. Sometimes even faster.

[StephanTLavavej]

I indeed observe QPF == 10M on my 4 physical machines, all Win10: #2085 (comment)

[barcharcraz]

Looks good to me.

I note that in this case the race on the static variable would seem benign, but we like to avoid even those races so since removing the static variable doesn't make much difference I prefer just keeping it removed.

[StephanTLavavej]

@barcharcraz Magic statics would avoid data races, but we avoid magic statics in product code, see #673 (comment) .

[StephanTLavavej]

I'm mirroring this to an MSVC-internal PR. Please notify me if any further changes are pushed.

[StephanTLavavej]

Thanks for optimizing this time-sensitive timing function! 😻 🚀 ⚡