DLPX-75470 estat zpl and arc_prefetch scripts need znode parameter (#61)

[brad-lewis]

Minor merge conflict but this brings 6.0/stage up to date with master.

I did some quick runs on 6.0/stage to make sure the scripts compile and run:

06/10/21 - 15:17:35 UTC

 Tracing enabled... Hit Ctrl-C to end.
   microseconds                                           zfs_read async
value range                 count ------------- Distribution ------------- 
[0, 10)                       173 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
[10, 20)                        3 |@                                       

   microseconds                                          zfs_write async
value range                 count ------------- Distribution ------------- 
[0, 10)                       401 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@     
[10, 20)                       41 |@@@@                                    
[20, 30)                        5 |@                                       
[30, 40)                        3 |@                                       
[40, 50)                        8 |@                                       
[50, 60)                        3 |@                                       
[70, 80)                        2 |@                                       
[90, 100)                       1 |@                                       

                                       iops(/s)  avg latency(us)       stddev(us)  throughput(k/s)
zfs_read async                               35                2                5                0
zfs_write async                              92                8               92                0


                                       iops(/s)  throughput(k/s)
total                                       128                0

06/10/21 - 15:16:41 UTC

06/10/21 - 15:16:46 UTC

prefetch hit count   : 22
   microseconds                                         arc read latency
value range                 count ------------- Distribution ------------- 
[4, 8)                          1 |@                                       
[8, 16)                         1 |@                                       

                                avg latency(us)
arc read latency                             10