Fix libjulia install name and libjulia-internal rpath on OS X

[jonathan-conder-sm]

Fixes #40246.

This PR makes 3 main changes:

• change the RPATH of libjulia-internal.dylib, by analogy with libjulia-internal.so
• set the install name of libjulia.dylib to libjulia.1.dylib
• change JL_LIBJULIA_SONAME to @rpath/libjulia.1.dylib on Mac

I'm not sure if all 3 are necessary but I think they're all good changes in any case. In particular #2 means you can package libjulia.1.dylib without a libjulia.dylib symlink.

I also removed JL_LIBJULIA_INTERNAL_SONAME because it seems to be unused.

I made a small test case to check that this fixes the issue (for me, at least).

It builds and runs a test program which embeds julia indirectly, via libtest.dylib. These both live in the parent directory of libjulia.dylib, with RPATHs set accordingly.

The test results can be viewed here. Note that src/mac_embedding_test/test.sh julia is the patched build, and prints sqrt(2.0) successfully. On the other hand src/mac_embedding_test/test.sh julia-1.6.7 uses the official Julia 1.6.7 build, and segfaults when libjulia-internal.dylib tries to get a handle to libjulia.dylib.

[staticfloat]

These look good to me! Can you also make a PR to master with the relevant changes there as well?

[jonathan-conder-sm]

These look good to me! Can you also make a PR to master with the relevant changes there as well?

Sure but it doesn't seem like this bug is present in master. Not sure why though, I'll take a look

[jonathan-conder-sm]

BTW this change might break ABI compatibility, not sure if you want to preserve that between minor/patch versions or something

[staticfloat]

BTW this change might break ABI compatibility, not sure if you want to preserve that between minor/patch versions or something

I see this as kind of a bug fix; the RPATH was just strictly wrong before. In terms of changing the SONAME, I think this is also something of a bugfix. :P @vtjnash do you agree?

[ViralBShah]

Let's merge this once #47220 appears to be ok for a few days on master.

[ViralBShah]

I suppose the old testers are unlikely to work on 1.6. It would be nice to have this run on macos64 CI.

@DilumAluthge What should we do here?

[vtjnash]

No v1.6 releases are planned