message: use temp_dir for FS test
diff: @@ -5,16 +5,16 @@ use std::fs::{File, remove_file};
  use std::io::{Read, Write};
  fn main() {
  - let path = "miri_test_fs.txt";
  + let path = std::env::temp_dir().join("miri_test_fs.txt");
  let bytes = b"Hello, World!\n";
  // Test creating, writing and closing a file (closing is tested when `file` is dropped).
  - let mut file = File::create(path).unwrap();
  + let mut file = File::create(&path).unwrap();
  // Writing 0 bytes should not change the file contents.
  file.write(&mut []).unwrap();
  file.write(bytes).unwrap();
  // Test opening, reading and closing a file.
  - let mut file = File::open(path).unwrap();
  + let mut file = File::open(&path).unwrap();
  let mut contents = Vec::new();
  // Reading 0 bytes should not move the file pointer.
  file.read(&mut []).unwrap();
  @@ -22,9 +22,9 @@ fn main() {
  file.read_to_end(&mut contents).unwrap();
  assert_eq!(bytes, contents.as_slice());
  // Removing file should succeed
  - remove_file(path).unwrap();
  + remove_file(&path).unwrap();
  // Opening non-existing file should fail
  - assert!(File::open(path).is_err());
  + assert!(File::open(&path).is_err());
  // Removing non-existing file should fail
  - assert!(remove_file(path).is_err());
  + assert!(remove_file(&path).is_err());
  }
  