Add alias File::set_modified as shorthand

Author: joshtriplett

library/std/src/fs.rs

@@ -638,6 +638,15 @@ impl File {
     pub fn set_times(&self, times: FileTimes) -> io::Result<()> {
         self.inner.set_times(times.0)
     }
+
+    /// Changes the modification time of the underlying file.
+    ///
+    /// This is an alias for `set_times(FileTimes::new().set_modified(time))`.
+    #[unstable(feature = "file_set_times", issue = "98245")]
+    #[inline]
+    pub fn set_modified(&self, time: SystemTime) -> io::Result<()> {
+        self.set_times(FileTimes::new().set_modified(time))
+    }
 }
 
 // In addition to the `impl`s here, `File` also has `impl`s for