am 4c4fa1a5: am 541a7804: am 490f03d5: am 3ea87c33: Fix build breakage for missing -Wcpp option on old GCC versions.

* commit '4c4fa1a57fcf7aaf174655532b19b813a7f43ad3':
  Fix build breakage for missing -Wcpp option on old GCC versions.