Suppress pio logs on non-component-root processes

[jayeshkrishna]

Making sure that we print out PIO logs only from rank 0 of each
component.

This bug was introduced in PR #2799.

Fixes #2839

[BFB]

[dqwu]

This change looks good to me.
Note, the output from the root process will be in cpl.log (not e3sm.log).

[dqwu]

@jgfouca
It is confirmed that shr_log_unit is redirected to cpl.log for rank 0.
For other ranks, it is redirected to e3sm.log.
Not sure if it was designed that way in CIME: cpl log instead of e3sm log.

[worleyph]

@dqwu , prior to the CIME update, PIO output of this sort went both to cpl.log:

  CPL              : pio_numiotasks =            8
  CPL              : pio_stride =           16
  CPL              : pio_root =            0
  CPL              : pio_iotype =            5
 
  OCN              : pio_numiotasks =            8
  OCN              : pio_stride =           16
  OCN              : pio_root =            0
  OCN              : pio_iotype =            5
 
  ICE              : pio_numiotasks =            8
  ICE              : pio_stride =           16
  ICE              : pio_root =            0
  ICE              : pio_iotype =            5
 
  ROF              : pio_numiotasks =            8
  ROF              : pio_stride =           16
  ROF              : pio_root =            0
  ROF              : pio_iotype =            5

and to e3sm.log:

  ATM              : pio_numiotasks =           42
  ATM              : pio_stride =           16
  ATM              : pio_root =            0
  ATM              : pio_iotype =            5
 
  LND              : pio_numiotasks =           43
  LND              : pio_stride =           16
  LND              : pio_root =            0
  LND              : pio_iotype =            5
 
  GLC              : pio_numiotasks =            1
  GLC              : pio_stride =            1
  GLC              : pio_root =            0
  GLC              : pio_iotype =            5
 
  WAV              : pio_numiotasks =            1
  WAV              : pio_stride =            1
  WAV              : pio_root =            0
  WAV              : pio_iotype =            5

  ESP              : pio_numiotasks =            1
  ESP              : pio_stride =            1
  ESP              : pio_root =            0
  ESP              : pio_iotype =            6

For some reason, the above information was output twice in each log file.

[worleyph]

@dqwu , our posts crossed :-). Your post explains why some go to one log file and the rest go to the other log file.

[jgfouca]

Thanks @jayeshkrishna !