Ignore failures of RLS on aarch64 Windows

src/bootstrap/dist.rs

@@ -1029,7 +1029,13 @@ impl Step for Rls {
         let rls = builder
             .ensure(tool::Rls { compiler, target, extra_features: Vec::new() })
             .or_else(|| {
-                missing_tool("RLS", builder.build.config.missing_tools);
+                // We ignore failure on aarch64 Windows because RLS currently
+                // fails to build, due to winapi 0.2 not supporting aarch64.
+                missing_tool(
+                    "RLS",
+                    builder.build.config.missing_tools
+                        || (target.triple.contains("aarch64") && target.triple.contains("windows")),
+                );
                 None
             })?;