Fix printing of PCI domain

[david-macmahon]

Only print the PCI domain if it is non-zero and print it using "%04x:" as the format string.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (8906152) 33.67% compared to head (09fbc37) 33.74%.
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #77      +/-   ##
==========================================
+ Coverage   33.67%   33.74%   +0.06%     
==========================================
  Files           5        5              
  Lines         962      963       +1     
==========================================
+ Hits          324      325       +1     
  Misses        638      638              

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[JBlaschke]

I just ran this on Perlmutter -- works fine.

I'm not sure what problem this fixes though. @david-macmahon maybe you can give more context.

[david-macmahon]

Before this PR the PCI domain was printed as a Char (i.e. '\x00') rather than as a hexadecimal integer (i.e. 0000). This PR prints the PCI domain as a hexadecimal integer, but only if it is not 0000. When printing to the terminal, the old (pre-PR) and new (post-PR) outputs look the same for PCI domain 0000 because the NUL character of the pre-PR output doesn't display anything and the post-PR behavior is not to print the PCI domain if it is 0000. If you redirect the pre-PR output to a file (or less) you will be able to see the errant NUL character.

[JBlaschke]

Sneaky! Thanks for spotting that.