Fix RPATH of libLLVM.so on FreeBSD and Linux

[vchuravy]

The RPATH of LLVM is wrong (JuliaPackaging/Yggdrasil#3703) after we move it to lib/julia.
This causes us to not find libz.so.

I see three options:

1. Fix RPATH on installation
2. Fix RPATH on build (time consuming)
3. Preload libz in the loader (more invasive)

I went with 1. since that fixes the wrong RPATH, without requiring a rebuild of LLVM or changing the loader.

[ararslan]

I can confirm that this fixes #42781 for me locally, but I'm now hitting #41943, so one of the changes in RC2 must have introduced that to release-1.7.

[vchuravy]

Also the failure on tester_freebs64:

ERROR: Unable to load dependent library /usr/home/julia/buildbot/w2_tester/tester_freebsd64/build/bin/../lib/julia/libjulia-internal.so.1
Message:/usr/home/julia/buildbot/w2_tester/tester_freebsd64/build/lib/julia/libLLVM-12jl.so: program header too large

@staticfloat any ideas?

[vchuravy]

I can confirm that this fixes #42781 for me locally, but I'm now hitting #41943, so one of the changes in RC2 must have introduced that to release-1.7.

Can you bisect?

[staticfloat]

program header too large

This is a known issue with using patchelf on FreeBSD. :(
NixOS/patchelf#153

[ararslan]

I'm now hitting #41943

wtf, now I'm getting it on v1.7.0-rc1 too, but only after the first time I run tests?

[vchuravy]

program header too large

This is a known issue with using patchelf on FreeBSD. :( NixOS/patchelf#153

@staticfloat Okay I now that preloading works, that might be the alternative? Otherwise does reducing the rpath entry length help, patchelf might then not need to relocate the header to the end?

[staticfloat]

Okay I now that preloading works, that might be the alternative?

We are going to do this anyway, eventually, once I finally get around to finishing up the JLL stdlib work.

Otherwise does reducing the rpath entry length help, patchelf might then not need to relocate the header to the end?

Yes, but this is kind of sensitive to things outside of our control. If we had a way to "pad" the program header, a la -headerpad_max_install_names on macOS, this would be a lot easier.

[haampie]

This shouldn't apply to external LLVM, it follows symlinks. Just hit this in Spack which sets the correct rpaths for all LLVM dependencies, but Julia deletes them and replaces them with $ORIGIN:$ORIGIN/.., that was surprising 😅.