`xlgamma.cpp`: Is it possible to use UCRT's `lgamma` now?

[frederick-vs-ja]

STL/stl/src/xlgamma.cpp

Line 6 in 7841cf8

// TRANSITION, ABI: This should be superseded by the CRT's lgamma().

The TRANSITION, ABI comment has been present since the initial commit. However, it doesn't seem ABI-breaking to switch to use UCRT's lgamma (and its f, l variants).

Can we switch to use lgamma? Or, if not, should this comment be more detailed?

[StephanTLavavej]

I think we can use the UCRT. We used to be overly scared of behavioral changes.