Probably unwanted Fallthrough in ckddasd.c

[AlgorithMan-de]

gcc 10.2 warns about switch cases that can fall through without explicitly allowing it to fall through. In ckddasd.c, line 1461 I think gcc has found a bug, because all the cases there fall through to the case that ultimately sets shift to 4. That doesn't look like it's intended. https://github.com/rbowler/spinhawk/blob/d3c5e350b5b19becfbb32c70db36e2a6dbc3be47/ckddasd.c#L1461