Add a new Makefile target check-wine-devel-vs-wine-staging that works
around a deficiency of Mk/Scripts/check-stagedir.sh that does not spot
entries in pkg-plist that move from being enabled only with the STAGING
option (%%STAGING%%foo/bar/file) to being there by default (foo/bar/file).

This has caused actual issues for users, so we need to regularly check
for such cases, which a simple check-wine-devel-vs-wine-staging will
now do, provided the staging directory is accessible.

PR: 220950