Some desktop environments are now checking for free space before
copying files to a destination.

To support this, the FUSE filesystem needs to convert the statvfs()
system call to the relevent PDUs from [MS-RDPEFS]

Chromium 130 won't save to our filesystem if we don't return a
max filename length.

Dummy parameters were tried for inode counts, but these do not seem to
be necessary. Not also that btrfs foes not return values for these
fields.