refactor: Move Apple SDK names to rustc_codegen_ssa:🔙:apple

compiler/rustc_codegen_ssa/src/errors.rs

@@ -738,13 +738,6 @@ pub enum ExtractBundledLibsError<'a> {
     ExtractSection { rlib: &'a Path, error: Box<dyn std::error::Error> },
 }
 
-#[derive(Diagnostic)]
-#[diag(codegen_ssa_unsupported_arch)]
-pub(crate) struct UnsupportedArch<'a> {
-    pub arch: &'a str,
-    pub os: &'a str,
-}
-
 #[derive(Diagnostic)]
 pub(crate) enum AppleDeploymentTarget {
     #[diag(codegen_ssa_apple_deployment_target_invalid)]