Migrate run-make/used to migrate.rs

Author: GuillaumeGomez

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -251,7 +251,6 @@ run-make/unknown-mod-stdin/Makefile
 run-make/unstable-flag-required/Makefile
 run-make/use-suggestions-rust-2018/Makefile
 run-make/used-cdylib-macos/Makefile
-run-make/used/Makefile
 run-make/volatile-intrinsics/Makefile
 run-make/wasm-exceptions-nostd/Makefile
 run-make/wasm-override-linker/Makefile

tests/run-make/used/Makefile

@@ -0,0 +1,7 @@
+use run_make_support::{cmd, rustc};
+
+fn main() {
+    rustc().opt_level("3").emit("obj").input("used.rs").run();
+
+    cmd("nm").arg("used.o").run().assert_stdout_contains("FOO");
+}