ds1963s-brute.c: Solve concurrency issues.

The software ds1963s implementation was a critical section, as the scratchpad
and some internal state variables would be overwritten.  Therefore, this either
needed to be locked, but to avoid this, we have duplicated the datastructures 8
times, such that every thread now uses its own ds1963s software implementation.

Signed-off-by: Ronald Huizer <r.huizer@xs4all.nl>