aco: fix WQM handling in nested loops
If on a nested loop
- the outer loop needs WQM but
- the inner loop doesn't need WQM and
- the break condition of the inner loop is computed in the outer loop then it could happen that we transitioned to Exact before entering the inner loop which could create an empty exec mask and lead to an infinite loop.
Fixes RDR2
This patch is a bit overkill in that it flags all blocks of the nested CF as needs_WQM, but on the other hand, we have to execute the complete nested CF in WQM anyway if something within it needs WQM. No changes to pipelinedb.