op: Add a default value for MPI_OP o_name

[jjhursey]

For user defined MPI_Op types the o_name field is never set. Some components use this field for verbose output, and leaving it undefined makes the output difficult to review. So this commit makes sure that it gets initialized in all paths.

open-mpi/ompi#1833

[jjhursey]

bot:label:Code-cleanup-low-priority
bot:milestone:v2.0.1

[ibm-ompi]

Build Failed with GNU compiler! Please review the log, and get in touch if you have questions.

Gist: https://gist.github.com/c84e7946a8ca619afdf1a7faae20aabb

[ibm-ompi]

Build Failed with XL compiler! Please review the log, and get in touch if you have questions.

Gist: https://gist.github.com/6d6eb8de75cf06ec6cb15129d7b8eeba

[jjhursey]

bot:ibm:retest

[ibm-ompi]

Build Failed with GNU compiler! Please review the log, and get in touch if you have questions.

Gist: https://gist.github.com/6f633992afd9bb64cdda25894c9f1765

[mellanox-github]

Test FAILed.
See http://bgate.mellanox.com/jenkins/job/gh-ompi-release-pr/1829/ for details.

[jjhursey]

bot:ibm:retest

[jjhursey]

bot:retest

[mellanox-github]

Test PASSed.
See http://bgate.mellanox.com/jenkins/job/gh-ompi-release-pr/1846/ for details.

[mellanox-github]

Test FAILed.
See http://bgate.mellanox.com/jenkins/job/gh-ompi-release-pr/1940/ for details.

[mellanox-github]

Test FAILed.
See http://bgate.mellanox.com/jenkins/job/gh-ompi-release-pr/1943/ for details.

[jjhursey]

bot:assign: @jsquyres
@jsquyres Can you review? I thought you already did, and it's a small change.

The mellanox failure is unrelated.
bot:retest

[jsquyres]

👍
bot:retest

[mellanox-github]

Test FAILed.
See http://bgate.mellanox.com/jenkins/job/gh-ompi-release-pr/1948/ for details.

[jsquyres]

Mellanox Jenkins failure is unrelated. Per the call today, @artpol84 is investigating.