process: remove debug perror() prints

[indutny]

fix #1128

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• Fedor Indutny

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[saghul]

LGTM. I wonder if we should still have them in debug builds?

[indutny]

@saghul I think no, we are returning error as an exit code, so it should be fine anyway.

[sam-github]

Thanks, Fedor.

[indutny]

Landed in c0c9480, thank you!