[llvm-branch-commits] [libcxx] release/18.x: Reapply [libcxx] [modules] Fix relative paths with absolute LIBCXX_INSTALL_MODULES_DIR (#86020) (PR #86197)

[Mark de Wever via llvm-branch-commits]

mordante wrote:

> @mordante Is the test failure legitimate?

I've checked and the test failure is unrelated to this patch.

https://github.com/llvm/llvm-project/pull/86197