Incorrect library load paths due to rpath patcher run on symlinks

[mbargull]

What happened?

In conda-build>=3.28.0, 1dc2470 replaced .os_utils.pyldd.is_codefile/.os_utils.*.codefile_type by direct calls to .os_utils.*.codefile_class which those functions wrapped.
For is_codefile/codefile_type the skip_symlinks parameter defaults to True whereas it is False for codefile_class which induced some unintended changes.
Notably, .post.post_process_shared_lib runs the rpath patcher on symlinks in conda-build>=3.28, which leads to invalid entries being set for the symlink targets in case the symlinks are located in different directories.

Case analysis at conda-forge/openmpi-feedstock#142 (comment) ff.
In that specific case, we have a lib/<target> and lib/<subfolder>/<symlink> -> lib/<target> for which lib/<target> gets rpath set to $ORIGIN/..:$ORIGIN/. instead of $ORIGIN/..:$ORIGIN/. if the symlink is processed after the actual target.
The issue was noticed because we ran into an bug with in patchelf which I could pinpoint to being introduced in NixOS/patchelf@42394e8 (i.e., affecting patchelf>=0.17.0.
(Others have run into issues introduced with that change; see NixOS/patchelf#446 ).

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Test and patch incoming.

[h-vetinari]

We ran into an apparent rpath problem when building boost with conda-build 3.28, which went away with conda-build 3.27. I cannot guarantee that it's the same bug, but it sounds related, and it would be good to verify/test that #5181 also fixes that issue.

[mbargull]

@h-vetinari, hm.. libboost doesn't have these subfolder issues since it's all flat in lib/.
This might be another bug :/ ...
Let me try if I can somewhat quickly find which change might've caused that issue.

[mbargull]

@h-vetinari, hm.. libboost doesn't have these subfolder issues since it's all flat in lib/. This might be another bug :/ ... Let me try if I can somewhat quickly find which change might've caused that issue.

For some reason this started to fail for me after the change from gh-5031 ...

[kenodegard]

Resolved in #5181, upcoming conda-build 24.1.2 patch release will include the fix