DroneCAN: update DSDL compiler

Fixes the following issues:

 * Compound array elements subject to tail array optimization could be
decoded incorrectly, causing a decode failure.

 * Invalid array lengths could be sent over the wire if a
longer-than-max array was encoded (though only the max number of
elements was sent).

 * Lengths were not validated when decoding arrays of compound elements
using TAO, causing memory corruption if an invalid length was received.

 * Union tags were not validated, causing undefined behavior if an
invalid tag was received.