Auto merge of #57429 - alexcrichton:fix-dist, r=Mark-Simulacrum
Auto merge of #57429 - alexcrichton:fix-dist, r=Mark-Simulacrum

Build LLVM with -static-libstdc++ on dist builds

This commit is intended on fixing a regression from #57286 where the
distributed LLVM shared library unfortunately depends on a dynamic copy
of libstdc++, meaning we're no longer as binary compatible as we
thought! This tweaks the build of LLVM as out distribution is slightly
different now, and is hoped to fix the issue.

Closes #57426

graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust