Merge branch 'acquires-seq'

This uses the sequence number from acquires when installing the SA. This
allows handling narrowing properly by changing the reqid and still
removing the temporary state in the kernel.  It also changes that
traffic selectors are reused during rekeying/recreation/reauthentication,
so narrowed selectors won't return to the wider configured TS because
there won't be any TS from triggering packets to narrow again.