Update nicstat.c
Update nicstat.c

Allows for one kstat (uint32_t) wrap during a sample interval - prevents wildly inaccurate data rate stats following that wrap.
Unit tests across wrap of consumed kstat data:

Test:
========
% ./build/amd64/nicstat -t 20 &
% while true ; do
        kstat tcp | grep outDataByte
        sleep 5
        done &

% scp /var/tmp/fug.tar gesheph@tcx32-09.us.oracle.com:/var/tmp

========

06:25:38    InKB   OutKB   InSeg  OutSeg Reset  AttF %ReTX InConn OutCon Drops
TCP         4.28 11464.8   119.6  4180.9  0.00  0.00 0.000   0.00   0.00  0.00
        outDataBytes                    3813019102
        outDataBytes                    3872846230
        outDataBytes                    3932640721
        outDataBytes                    3992499741
06:25:58    InKB   OutKB   InSeg  OutSeg Reset  AttF %ReTX InConn OutCon Drops
TCP         4.24 11492.4   119.9  4154.2  0.00  0.00 0.000   0.05   0.00  0.00
        outDataBytes                    4052253245
        outDataBytes                    4112416693
        outDataBytes                    4172181761
        outDataBytes                    4232014681
06:26:18    InKB   OutKB   InSeg  OutSeg Reset  AttF %ReTX InConn OutCon Drops
TCP         4.23 11492.4   119.8  4157.6  0.00  0.00 0.000   0.00   0.00  0.00
        outDataBytes                    4291824765
        outDataBytes                    56690497 ------>> has wrapped between samples
        outDataBytes                    116504629
        outDataBytes                    176294109
06:26:38    InKB   OutKB   InSeg  OutSeg Reset  AttF %ReTX InConn OutCon Drops
TCP         4.21 11492.4   119.7  4156.7  0.00  0.00 0.000   0.00   0.00  0.00
        outDataBytes                    236151869
        outDataBytes                    295929765
        outDataBytes                    355241781
06:26:58    InKB   OutKB   InSeg  OutSeg Reset  AttF %ReTX InConn OutCon Drops
TCP         4.27 11462.4   119.5  4190.0  0.00  0.00 0.000   0.00   0.00  0.00
        outDataBytes                    414868405
scotte/nicstat,scotte/nicstat