Add a default implementation for CodegenBackend::link

As a side effect this should add raw-dylib support to cg_gcc as the
default ArchiveBuilderBuilder that is used implements
create_dll_import_lib. I haven't tested if the raw-dylib support
actually works however.

compiler/rustc_codegen_cranelift/src/archive.rs

@@ -1,12 +0,0 @@
-use rustc_codegen_ssa::back::archive::{
-    ArArchiveBuilder, ArchiveBuilder, ArchiveBuilderBuilder, DEFAULT_OBJECT_READER,
-};
-use rustc_session::Session;
-
-pub(crate) struct ArArchiveBuilderBuilder;
-
-impl ArchiveBuilderBuilder for ArArchiveBuilderBuilder {
-    fn new_archive_builder<'a>(&self, sess: &'a Session) -> Box<dyn ArchiveBuilder + 'a> {
-        Box::new(ArArchiveBuilder::new(sess, &DEFAULT_OBJECT_READER))
-    }
-}

compiler/rustc_codegen_cranelift/src/lib.rs

@@ -43,7 +43,6 @@ use rustc_codegen_ssa::CodegenResults;
 use rustc_codegen_ssa::back::versioned_llvm_target;
 use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_data_structures::profiling::SelfProfilerRef;
-use rustc_errors::ErrorGuaranteed;
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_session::Session;
@@ -56,7 +55,6 @@ use crate::prelude::*;
 mod abi;
 mod allocator;
 mod analyze;
-mod archive;
 mod base;
 mod cast;
 mod codegen_i128;
@@ -249,17 +247,6 @@ impl CodegenBackend for CraneliftCodegenBackend {
             self.config.borrow().as_ref().unwrap(),
         )
     }
-
-    fn link(
-        &self,
-        sess: &Session,
-        codegen_results: CodegenResults,
-        outputs: &OutputFilenames,
-    ) -> Result<(), ErrorGuaranteed> {
-        use rustc_codegen_ssa::back::link::link_binary;
-
-        link_binary(sess, &crate::archive::ArArchiveBuilderBuilder, &codegen_results, outputs)
-    }
 }
 
 fn target_triple(sess: &Session) -> target_lexicon::Triple {