MFC r272284

MFC r272284

   Fix integer truncation in affecting systat -ifstat

   The "systat -ifstat" command was using a u_int to store byte counters.
   With a 10Gbps or faster interface, this overflows within the default
   5 second refresh period.  Switch to using a uint64_t across the board,
   which matches the size used for all counters as of r263102.

   PR:           182448
   MFC after:    1 week
   Sponsored by: Sandvine Inc

git-svn-id: svn://svn.freebsd.org/base/stable/10@279473 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f