Don't pass Arc<Config> to runtest::run

This function doesn't need its own clone of the `Arc`, and can just take a
reference instead.

src/tools/compiletest/src/executor.rs

@@ -224,7 +224,7 @@ fn new(test: &CollectedTest) -> Self {
     fn run(&self, stdout: &dyn ConsoleOut, stderr: &dyn ConsoleOut) {
         __rust_begin_short_backtrace(|| {
             crate::runtest::run(
-                Arc::clone(&self.config),
+                &self.config,
                 stdout,
                 stderr,
                 &self.testpaths,

src/tools/compiletest/src/runtest.rs

@@ -6,7 +6,6 @@
 use std::io::prelude::*;
 use std::io::{self, BufReader};
 use std::process::{Child, Command, ExitStatus, Output, Stdio};
-use std::sync::Arc;
 use std::{env, fmt, iter, str};
 
 use build_helper::fs::remove_and_create_dir_all;
@@ -110,7 +109,7 @@ fn dylib_name(name: &str) -> String {
 }
 
 pub fn run(
-    config: Arc<Config>,
+    config: &Config,
     stdout: &dyn ConsoleOut,
     stderr: &dyn ConsoleOut,
     testpaths: &TestPaths,