message: Use char literals insted of integer constants
  Summary: Minor code cleanup.
diff: @@ -223,8 +223,8 @@ impl<'v> StarlarkValue<'v> for StarlarkStr {
  } else {
  // safe because we know the following values are all lower-ascii bytes
  let byte_buffer = unsafe { buffer.as_mut_vec() };
  - if x == 34 || x == 39 || x == 92 {
  - byte_buffer.push(92); // character for \
  + if x == b'"' || x == b'\'' || x == b'\\' {
  + byte_buffer.push(b'\\');
  }
  byte_buffer.push(x);
  }
  