Auto merge of #121967 - nikic:libllvm-linker-script, r=Mark-Simulacrum

Replace libLLVM symlink with linker script

It turns out that the libLLVM-N.so -> libLLVM.so.N.1 symlink is also needed when projects like miri link against librustc_driver.so. As such, we have to distribute it in real rustup components like rustc-dev, rather than only for download-ci-llvm.

To avoid actually distributing symlinks (which are not supported or not fully supported by the rustup infrastructure) replace it with a linker script that does the same thing instead.

Fixes rust-lang/rust#121889.

r? `@cuviper`