Next free block from FSINFO structure ignored

[boeckmann]

Despite being read into the registers, the next free cluster (aka. cluster to start the search for free clusters from) is not stored in the DDSC structure.

https://github.com/SvarDOS/edrdos/blob/2c73ebb1c639bb57abfafa9e45874e6714778f2f/drdos/buffers.a86#L1706

This may be an oversight or by intention. I tend to think that it is an oversight and should be corrected. Otherwise, it does not harm to start the free cluster search at the first cluster.