emulators/wine7: New port, cloning emulators/wine

Wine 8 has been released late last year and we have not seen
corresponding updates to wine-devel and the main wine port yet,
partly because there's unresolved breakage on FreeBSD/i386.

To unstall the situation, create emulators/wine7 as a clone of
emulators/wine for those who want/need that version. This will
allow moving the latter forward.

PR: 272710, 271201
Suggested by: lwhsu