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

https://github.com/microsoft/STL/blob/7841cf88ff9af837fb980f2d2d4ac0f267e714c7/stl/src/xlgamma.cpp#L6

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?