fuse2 is no longer maintained, and the various Linux distros want all
packages to move to fuse3. So, let's add fuse3 support.
Moreover, as it's been over 5 years since fuse3 was released, it doesn't
seem worth it to support both fuse2 and fuse3. So, remove support for
fuse2, and just support fuse3.
Note: as before, WIM mounting support can still be disabled by
configuring --without-fuse. That removes the dependency.
git://wimlib.net / wimlib / commit