Add LLVM 19 and 20 bootstrap shards.

[maleadt]

No description provided.

[maleadt]

Error loading shared library libxml2.so.16: No such file or directory (needed by /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1)
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlDocGetRootElement: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlNewNs: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlDocSetRootElement: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlCopyNamespace: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlSetGenericErrorFunc: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlStrdup: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlReadMemory: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlUnlinkNode: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlNewDoc: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlFreeDoc: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlNewProp: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlFreeNs: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlDocDumpFormatMemoryEnc: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlFreeNode: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlAddChild: symbol not found
Error relocating /opt/x86_64-linux-musl/bin/../lib/libLLVM.so.20.1: xmlFree: symbol not found

Yet libxml2 is included...

❯ tar -tvf LLVMBootstrap.*.x86_64-linux-musl.tar.gz | grep xml
drwxr-xr-x 0/0               0 1970-01-01 01:00 include/libxml2
drwxr-xr-x 0/0               0 1970-01-01 01:00 include/libxml2/libxml
drwxr-xr-x 0/0               0 1970-01-01 01:00 lib/cmake/libxml2
drwxr-xr-x 0/0               0 1970-01-01 01:00 share/gtk-doc/html/libxml2
lrwxr-xr-x 0/0               0 1970-01-01 01:00 x86_64-linux-musl/lib64/libxml2.so -> libxml2.so.16.0.1
-rwxr-xr-x 0/0         5667928 1970-01-01 01:00 x86_64-linux-musl/lib64/libxml2.so.16.0.1
lrwxr-xr-x 0/0               0 1970-01-01 01:00 x86_64-linux-musl/lib64/libxml2.so.2 -> libxml2.so.16.0.1

Looks like the build switched from linking against libxml2.so.2 to libxml2.so.16.

[giordano]

Xml2 had a breaking change

[giordano]

See JuliaPackaging/Yggdrasil#10965

[maleadt]

OK, so what are you suggesting? Superficially it seems like there's just a library symlink missing.

[giordano]

I haven't inspected yet how xml2 is used here, but we consistently should make sure that we use a compatible version at all time.

[maleadt]

Seems to work with the additional libxml2 symlink (or at least passes whatever tests are done here).

[maleadt]

In addition, PoCL builds find with the LLVM 20 toolchain added here.

@giordano Is there anything else you want me to check?