Draft: Demonstrate broken symlinks without /proc/fd support in 4.19

In 4.19 symlinks to directories are broken on systems without support for "Safe File Handle Reopen" like AIX. This MR merely demonstrates the problem by adjusting the no-opath runner, marking failing tests as "to-be-skipped" and finally marking the symlinks working again with the final commit that contains the core fix.

The corresponding fixes for master are in !3455 (closed).