Fix clippy::print_with_newline

Author: Xanewok

src/librustc_errors/emitter.rs

@@ -1339,7 +1339,7 @@ impl EmitterWriter {
         }
 
         let mut dst = self.dst.writable();
-        match write!(dst, "\n") {
+        match writeln!(dst) {
             Err(e) => panic!("failed to emit error: {}", e),
             _ => {
                 match dst.flush() {
@@ -1598,7 +1598,7 @@ fn emit_to_destination(rendered_buffer: &[Vec<StyledString>],
             dst.reset()?;
         }
         if !short_message && (!lvl.is_failure_note() || pos != rendered_buffer.len() - 1) {
-            write!(dst, "\n")?;
+            writeln!(dst)?;
         }
     }
     dst.flush()?;

src/libsyntax/print/pp.rs

@@ -497,7 +497,7 @@ impl<'a> Printer<'a> {
 
     pub fn print_newline(&mut self, amount: isize) -> io::Result<()> {
         debug!("NEWLINE {}", amount);
-        let ret = write!(self.out, "\n");
+        let ret = writeln!(self.out);
         self.pending_indentation = 0;
         self.indent(amount);
         ret