message: Add new/old rustflags to fingerprint log.
diff: @@ -653,7 +653,11 @@ impl Fingerprint {
  bail!("profile configuration has changed")
  }
  if self.rustflags != old.rustflags {
  - bail!("RUSTFLAGS has changed")
  + bail!(
  + "RUSTFLAGS has changed: {:?} != {:?}",
  + self.rustflags,
  + old.rustflags
  + )
  }
  if self.metadata != old.metadata {
  bail!("metadata changed")
  