Warnings for possibly lossy conversions are currently disabled on Windows.

There are 290 files that produce this warning, and with Hotspot on Windows (x64) consisting of about 1100 files, it means that there are ~800 files that are good today.

We can protect these good files by enabling the warnings globally for hotspot, and then disabling the warnings locally for these 290 files.

In followup issues, warnings could be fixed on a per-file basis.