Add support for ldpaths detection on macOS via DYLD_FALLBACK_LIBRARY_PATH

[mjsteinbaugh]

This proposed pull request parses the etc/ldpaths file in R.home() for DYLD_FALLBACK_LIBRARY_PATH on macOS.

I've confirmed that this works on my machine after testing with python3 setup.py install.

Best,
Mike

[mjsteinbaugh]

Attempts to address related issue #413

[mjsteinbaugh]

For reference, this patch is now applied in koopa:
https://github.com/acidgenomics/koopa/blob/main/lang/bash/include/install/common/shared/radian.sh

[randy3k]

As indicated in the ldpaths file.

## This is DYLD_FALLBACK_LIBRARY_PATH on Darwin (macOS) and
## LD_LIBRARY_PATH elsewhere.
## However, on macOS >=10.11 (if SIP is enabled, the default), the
## environment value will not be passed to a script such as R.sh, so
## would not seen here.

I thought that this trick no longer works for macOS >=10.11 with sip, apparently it is not the case?

[mjsteinbaugh]

@randy3k That patch works on my Mac running Ventura 13.5 with SIP enabled.

This is also a known issue with RStudio, which they're working to address in a new release:
rstudio/rstudio#13085

[randy3k]

Oh, I think I have been misunderstanding the text in ldpaths for years. Actually it meant that we have to set the variable manually, the variable will not be passed automatically.

Thanks for raising it. Will take a look later today :)

[randy3k]

I think we should still restrict ourself to non-window.

For example

 if not sys.platform.startswith("win"):

[mjsteinbaugh]

Agreed yeah that makes sense

[randy3k]

Do you want to do the edit?

[mjsteinbaugh]

@randy3k Sure let me add that, 1 sec