rustc silently ignores failures in dsymutil

[gparker42]

On macOS rustc runs dsymutil to generate debug info files. This invocation incorrectly ignores dsymutil's output and exit status. rustc thus succeeds even if dsymutil fails or crashes.

Example: in #78657, dsymutil crashed and left behind a corrupt .dSYM file. rustc nevertheless succeeded, thereby confusing the user after the debugger ignored that bad debug info.

[gparker42]

rustc ignoring process::Output.status:

// compiler/rustc_codegen_ssa/src/back/link.rs:765
if let Err(e) = Command::new("dsymutil").arg(out_filename).output() {
    sess.fatal(&format!("failed to run dsymutil: {}", e))
}

[jryans]

@rustbot claim