[rpm] Capture the output of 'rpm --showrc'

[jcastill]

This request adds the output of --showrc to sos
so we can verify the default values of options set
via rpmrc and macros config files.

Resolves: RHBZ#1921496
Resolves: #2388

Signed-off-by: Jose Castillo jcastillo@redhat.com

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[TurboTurtle]

Does this really need to be gated behind a plugin option? We usually reserve those options for long running items, potentially sensitive collections, or historically ones that could make changes to the system (before the addition of --allow-system-changes and the like).

From quick testing this looks like it should be safe for a default collection.

[pmoravec]

I do agree that the extra option (though enabled by default) is bit redundant - I cant figure out a use case when one would need to prevent collecting the cmdoutput.

[jcastill]

I chose this approach to make sure that it was consistent with the other options, but you are right, so let me re-send this PR.