Update to Wine 6.0 RC2, which brings bug fixes only since we're in code
freeze.

Wine Staging now uses the same version designation as Wine itself after
a report of mine, so revert special casing STAGING_DISTFILES; similarly
my two patches files/extrapatch-dlls-ntdll-unix-file.c and
files/extrapatch-staging-server-fd.c are now upstream, so remove them.