WIP: fixes a comp failure

[demarle]

Was getting a linker shm_open symbol missing without this.

Type of change

• [ ] Bug fix~~ ~~* [ ] New feature~~ ~~* [ ] Documentation update~~ ~~* [ ] Other~~

How Has This Been Tested?

I've only compiled and locally run the branch on my workstation. Ubuntu 20.04. Visit 3.3.0 tag build fine there, develop did not.

Checklist:

• [ ] I have followed the style guidelines of this project.~~
• [ ] I have performed a self-review of my own code.~~
• [ ] I have commented my code where applicable.~~ ~~- [ ] I have updated the release notes.~~ ~~- [ ] I have made corresponding changes to the documentation.~~ ~~- [ ] I have added debugging support to my changes.~~ ~~- [ ] I have added tests that prove my fix is effective or that my feature works.~~
• [ ] I have confirmed new and existing unit tests pass locally with my changes.~~ ~~- [ ] I have added new baselines for any new tests to the repo.~~
• [ x] I have NOT made any changes to protocol or public interfaces in an RC branch.~~
• [ ] I have assigned reviewers (see VisIt's PR procedures for more information).~~