FastFAT fails to unset the clean shutdown bit (FAT32)

When mounting a clean shutdown volume (which thus has the clean shutdown bit set), FastFAT is supposed to unset the clean shutdown bit, so that, in case of abnormal stop, the FS is seen dirty.

But, for FAT32, FastFAT fails to do so, as the clean shutdown mask is improperly set, and thus, cannot be written to the disk.

This is not to be fixed yet, as long as chkdsk process isn't fixed.