Fix some new Clippy complaints

Author: pkgw

crates/xdv/src/lib.rs

@@ -250,11 +250,7 @@ impl<T: XdvEvents> XdvParser<T> {
             if n_in_buffer != 0 && n_consumed == 0 {
                 // We're going to need a bigger buffer in order to handle whatever
                 // we're reading. Let's double it.
-                let len = buf.len();
-                buf.reserve(len);
-                unsafe {
-                    buf.set_len(2 * len);
-                }
+                buf.resize(2 * buf.len(), 0);
             }
 
             if n_read == 0 {

src/driver.rs

@@ -1550,7 +1550,7 @@ impl ProcessingSession {
             status.note_highlighted(
                 "Writing ",
                 &format!("`{}`", real_path.display()),
-                &format!(" ({})", byte_len.get_appropriate_unit(true).to_string()),
+                &format!(" ({})", byte_len.get_appropriate_unit(true)),
             );
 
             let mut f = File::create(&real_path)?;