[libjulia] bump 1.12 to beta3 and update 1.13-dev

[benlorenz]

I guess we need this to work towards fixing GAP and CxxWrap errors on nightly. (And I think bumping 1.12 in the process is also reasonable)

cc: @fingolfin @lgoettgens @barche

[fingolfin]

Looks good to me thank you

[lgoettgens]

Just as a note: The julia PR (JuliaLang/julia#58131) that made rebuilding for nightly necessary will get backported to 1.12. This should not block this PR whatsoever, but it will probably mean that we need another rebuild in the near future

[benlorenz]

Only one failure:

[11:45:02] /opt/i686-w64-mingw32/bin/../lib/gcc/i686-w64-mingw32/9.1.0/../../../../i686-w64-mingw32/bin/ld: ./llvm-Compression.dbg.obj: in function `ZN4llvm11compression4zlib8compressENS_8ArrayRefIhEERNS_15SmallVectorImplIhEEi':
[11:45:02] /workspace/srcdir/julia/src/llvm-Compression.cpp:110: undefined reference to `compressBound'
[11:45:02] /opt/i686-w64-mingw32/bin/../lib/gcc/i686-w64-mingw32/9.1.0/../../../../i686-w64-mingw32/bin/ld: /workspace/srcdir/julia/src/llvm-Compression.cpp:112: undefined reference to `compress2'

We might be missing zlib in some linker command somewhere. (but only on 32bit windows ...?)

[giordano]

Llvm 20 needs zstd

[fingolfin]

Unfortunately still fails with the same (?) error

[barche]

Adding -lz to the LDFLAGS seems to fix it, but I'm not sure it's a good idea or just covering up the real cause.

[benlorenz]

Adding -lz to the LDFLAGS seems to fix it, but I'm not sure it's a good idea or just covering up the real cause.

I added -lz in a slightly more targeted way, for LLVMLINK.

This issue might happen because we are overriding RT_LLVMLINK, as to why this happens on 32bit windows only:
The corresponding object file with the missing symbol is from a workaround for 32 bit windows added here: https://github.com/JuliaLang/julia/pull/58344/files#diff-3e2513390df543315686d7c85bd901ca9256268970032298815d2f893a9f0685R219-R225
It is also possible that the flags are missing in general for that architecture when doing a USE_SYSTEM_LLVM build, but I don't want to try that (or spend much more time with the Makefiles).