buildall: name CMD-xx.COM after the FreeDOS LANG codes (PL, SV, SL, SR, UK, PB) `buildall.bat` names the language builds with its own abbreviations (`PO` Polish, `SE` Swedish, `SI` Slovene, `Ser` Serbian, `UKR` Ukrainian, `PTR` Brazilian Portuguese), so the package contains e.g. `NLS\CMD-PO.COM`. Everything that picks the localized shell looks for `CMD-%LANG%.COM`: - `NLS\MAKECMD.BAT` in the FreeCOM package itself (`if exist cmd-%lang%.com ...`), - the FDI-x86 and FDI installers (`if not exist ...\CMD-%LANG%.COM goto NoCommand`). With `LANG=PL` (or SV, SL, SR, UK, PB) nothing matches and the English COMMAND.COM stays installed. This PR only renames those six entries to the FreeDOS language codes (as in fd-nls `LangCode.md`). The other names already match; `YUG` (yu437) has no FreeDOS language code and is left as is. `strings/pt.lng` is not built by `buildall.bat` at all (it is in `ci_build.sh`) — left unchanged. Found while testing the Polish Floppy Edition (T2610): the installer looked for `CMD-PL.COM` and the package had `CMD-PO.COM`.
