Function copy_codegen_backends_to_sysroot 

fn copy_codegen_backends_to_sysroot(
    builder: &Builder<'_>,
    stamp: BuildStamp,
    target_compiler: Compiler,
)

Creates the codegen-backends folder for a compiler that’s about to be assembled as a complete compiler.

This will take the codegen artifacts recorded in the given stamp and link them into an appropriate location for target_compiler to be a functional compiler.