Tweaks to allow builds to work with just rpath (not LD_LIBRARY_PATH)

[pmolodo]

Description (this won't be part of the changelog)

Tweaks to allow builds to work with just rpath.

Changelog

Fixed

• Tweaks to allow builds to work with just rpath.

Checklist (Please do not remove this line)

• [X] Make sure the Title and Description of the PR make sense and provide sufficient context for your work
• [X] Do any added files have the correct AL Apache Licence Header?
• [X] Are there Doxygen comments in the headers?
• [x] Are any new features, behaviour changes documented in the .md format documentation?
• [X] Have you added, updated tests to cover new features and behaviour changes?
• [X] Have you filled out at least one changelog entry?