darshan does not understand symlinks, consider using realpath

Darshan is currently confused by symlinks used on Theta at ALCF. Theta project directories are symlinks to the underlying Lustre mount point that host the files. The Darshan Lustre module is unable to associate files that are referenced via the projects symlink since they do not match the mount point Darshan associates with Lustre.

We should investigate whether realpath overheads are reasonable enough that we could use it to fully resolve user file paths and avoid this symlink issue.