test/mpi/io: Check status after zero-byte read

[raffenet]

Pull Request Description

Until [4b7d553], ROMIO was failing to fill in the status object
for zero-byte operations. See #2332.

Co-authored-by: Jeff Hammond [email protected]

Expected Impact

Author Checklist

• Reference appropriate issues (with "Fixes" or "See" as appropriate)
• Remove xfail from the test suite when fixing a test
• Commits are self-contained and do not do two things at once
• Commit message is of the form: module: short description and follows good practice
• Passes whitespace checkers
• Passes warning tests
• Passes all tests
• Add comments such that someone without knowledge of the code could understand
• Add Devel Docs in the doc/ directory for any new code design

[raffenet]

I stumbled across this when searching through some issues. The test was nearly complete so I figured polish it up and submit.
test:jenkins/ch3/tcp

[raffenet]

test:jenkins/ch3/tcp

[roblatham00]

Great! thanks for adding this.