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
Ensure that ixl_flush() uses a defined register on VFs

In some code that is shared between the ixl(4) and ixlv(4) drivers,
a macro hard-coded a register offset that was not valid on ixlv devices.
Fix this by having each driver define a variable that contains the correct
offset.

Reviewed by:	Eric Joyner <ricera10 AT gmail.com>
MFC after:	3 days
Sponsored by:	Sandvine Inc
When setting environment variables in the atrun script, use the
"export foo=bar" form instead of "foo=bar; export foo" since the
former allows the shell to catch variable names that are not valid
shell identifiers.  This will cause /bin/sh to exit with an error
(which gets mailed to the at user) and it will not run the script.

Obtained from:	OpenBSD (r1.63 millert)
MFC after:	3 days
Sigh, remove a line that needs to be removed along with previous commit.

Submitted by:	mjg
MFC after:	3 days
X-MFC-with:	272288