mailmap: Add another old mail address I used.

.mailmap

@@ -9,7 +9,7 @@
 <josh@itanimul.li> <joshdk@obe.tv>
 <michael@niedermayer.cc> <michaelni@gmx.at>
 <linjie.fu@intel.com> <fulinjie@zju.edu.cn>
-<ceffmpeg@gmail.com> <cehoyos@ag.or.at>
+<ceffmpeg@gmail.com> <cehoyos@ag.or.at> <cehoyos@rainbow.studorg.tuwien.ac.at>
 <ffmpeg@gyani.pro> <gyandoshi@gmail.com>
 <atomnuker@gmail.com> <rpehlivanov@obe.tv>
 <zhong.li@intel.com> <zhongli_dev@126.com>