Function llvm_optimize

pub(crate) unsafe fn llvm_optimize(
    cgcx: &CodegenContext<LlvmCodegenBackend>,
    dcx: DiagCtxtHandle<'_>,
    module: &ModuleCodegen<ModuleLlvm>,
    config: &ModuleConfig,
    opt_level: OptLevel,
    opt_stage: OptStage,
) -> Result<(), FatalError>