reader_concurrency_semaphore: inactive_read_handle: swap definition order
reader_concurrency_semaphore: inactive_read_handle: swap definition order

For using boost::intrusive::list for _inactive_reads.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla