Convert Intos to Froms.

src/libstd/path.rs

@@ -1349,9 +1349,9 @@ impl From<Box<Path>> for PathBuf {
 }
 
 #[stable(feature = "box_from_path_buf", since = "1.18.0")]
-impl Into<Box<Path>> for PathBuf {
-    fn into(self) -> Box<Path> {
-        self.into_boxed_path()
+impl From<PathBuf> for Box<Path> {
+    fn from(p: PathBuf) -> Box<Path> {
+        p.into_boxed_path()
     }
 }