Remove stdarch submodule checkout

src/bootstrap/src/core/build_steps/check.rs

@@ -67,8 +67,6 @@ impl Step for Std {
             return;
         }
 
-        builder.require_submodule("library/stdarch", None);
-
         let stage = self.custom_stage.unwrap_or(builder.top_stage);
 
         let target = self.target;

src/bootstrap/src/core/build_steps/clippy.rs

@@ -141,8 +141,6 @@ impl Step for Std {
     }
 
     fn run(self, builder: &Builder<'_>) {
-        builder.require_submodule("library/stdarch", None);
-
         let target = self.target;
         let compiler = builder.compiler(builder.top_stage, builder.config.host_target);
 

src/bootstrap/src/core/build_steps/compile.rs

@@ -197,8 +197,6 @@ impl Step for Std {
             return;
         }
 
-        builder.require_submodule("library/stdarch", None);
-
         let mut target_deps = builder.ensure(StartupObjects { compiler, target });
 
         let compiler_to_use = builder.compiler_for(compiler.stage, compiler.host, target);

src/bootstrap/src/lib.rs

@@ -518,7 +518,7 @@ impl Build {
 
             // Make sure we update these before gathering metadata so we don't get an error about missing
             // Cargo.toml files.
-            let rust_submodules = ["library/backtrace", "library/stdarch"];
+            let rust_submodules = ["library/backtrace"];
             for s in rust_submodules {
                 build.require_submodule(
                     s,