In the attached test case we ended up not updating a leftover
MATCH jump in the unreachable_free block. There's different ways
this can be addressed, but in this case we can just make sure that
a new block is started after the loop free, which will allow it
to be dropped as unreachable. We only need to retain the free
itself for live-range reconstruction.
Fixes oss-fuzz #39516.
This would end up taking the successors_count=2 case, even though
we need to treat SWITCH and MATCH differently. This incorrectly
marked a block as FOLLOW, resulting in incorrect block pass
optimization.
Fixes oss-fuzz #39380.
