Compaction has to find the oldest level 0 segment for compaction. It
iterates over the level 0 segments by their manifest entry's btree key.
It was incorrectly incrementing the btree search key. It was
incrementing the first key stored in the entry, but that's not the least
significant field. The seq is the least significant field so this
iteration could skip over segments written at different times with the
same first key.
The fix to have it visit all the entries is to increment the lowest
precision seq field.
Right now we have a single level 0 segment so this code never actually
matters.
Signed-off-by: Zach Brown <zab@versity.com>