Reduce allocation in tsmKeyIterator.Next
Reduce allocation in tsmKeyIterator.Next

This reuses some intermediate buffers and structs while compacting
files.

benbjohnson/influxdb,nooproblem/influxdb,influxdb/influxdb,linearb/influxdb,influxdb/influxdb,influxdb/influxdb,influxdb/influxdb,vladlopes/influxdb,mark-rushakoff/influxdb,vladlopes/influxdb,influxdata/influxdb,benbjohnson/influxdb,influxdb/influxdb,mark-rushakoff/influxdb,nooproblem/influxdb,mark-rushakoff/influxdb,nooproblem/influxdb,nooproblem/influxdb,li-ang/influxdb,influxdata/influxdb,mark-rushakoff/influxdb,benbjohnson/influxdb,linearb/influxdb,benbjohnson/influxdb,linearb/influxdb,li-ang/influxdb,mark-rushakoff/influxdb,mark-rushakoff/influxdb,linearb/influxdb,nooproblem/influxdb,vladlopes/influxdb,influxdb/influxdb,vladlopes/influxdb,linearb/influxdb