[C++] Add performance stats for --regen
[C++] Add performance stats for --regen

shinh/kati,danw/kati,colincross/kati,danw/kati,colincross/kati,pombredanne/kati,colincross/kati,shinh/kati,colincross/kati,colincross/kati,pombredanne/kati,shinh/kati,pombredanne/kati,google/kati,google/kati,pombredanne/kati,shinh/kati,danw/kati,colincross/kati,google/kati,danw/kati,shinh/kati,google/kati,shinh/kati,danw/kati,pombredanne/kati,danw/kati,google/kati,pombredanne/kati