Consider build Julia with multiple system LLVM libraries.

[o01eg]

Currently LLVM library name is hardcoded to be libLLVM but in some configuration like Gentoo LLVM builds with BUILD_SHARED_LIBS=ON so it have a multiple libraries none of them named libLLVM.

It causes error while linking which was fixed by with Gentoo's patch for Julia but later it causes error on step symlink_libLLVM in base/Makefile.

[ihnorton]

For the multiple-symbol issue issue see #25597

There is an option to use system LLVM, but it is strongly discouraged because Julia carries a number of functional and bug fix-related LLVM patches.

[o01eg]

I have an different issue, not with symbols.
I don't have a system libLLVM.so binary. I have multiple binaries libraries libLLVM*.so in LLVM's libdir provided by LLVM installation.

[yuyichao]

Multiple system (/external) llvm is supported. AFAICT the only issue is #19443, which require patches on mac I believe.