cleanup: make run-make test use run_in_tmpdir

We had an issue on our LLVM-head Rust builder where it got stuck with
this test failing because it was reusing the tmpdir between runs and
something broke the incremental compile. Everything seems to work fine
with run_in_tmpdir in this test. tests/run-make/uefi-qemu also uses the
same tmpdir across runs, but I don't have the right environment to test
that so I didn't try fixing it. That is the only use of
std::env::temp_dir left in run-make tests after this fix.

Author: durin42

tests/run-make/rustdoc-scrape-examples-paths/rmake.rs

@@ -1,16 +1,16 @@
 //! Test to ensure that the rustdoc `scrape-examples` feature is not panicking.
 //! Regression test for <https://github.com/rust-lang/rust/issues/144752>.
 
-use run_make_support::{cargo, path, rfs};
+use run_make_support::cargo;
+use run_make_support::scoped_run::run_in_tmpdir;
 
 fn main() {
     // We copy the crate to be documented "outside" to prevent documenting
     // the whole compiler.
-    let tmp = std::env::temp_dir();
-    let test_crate = tmp.join("foo");
-    rfs::copy_dir_all(path("foo"), &test_crate);
-
-    // The `scrape-examples` feature is also implemented in `cargo` so instead of reproducing
-    // what `cargo` does, better to just let `cargo` do it.
-    cargo().current_dir(&test_crate).args(["doc", "-p", "foo", "-Zrustdoc-scrape-examples"]).run();
+    std::env::set_current_dir("foo").unwrap();
+    run_in_tmpdir(|| {
+        // The `scrape-examples` feature is also implemented in `cargo` so instead of reproducing
+        // what `cargo` does, better to just let `cargo` do it.
+        cargo().args(["doc", "-p", "foo", "-Zrustdoc-scrape-examples"]).run();
+    })
 }