dog: use -T as the option for showing elapsed time

Currently, "-t" has been used as the option abbr for both showing
elapsed time of executing dog command and enabling strict mode.
"-t" for strict mode is already available in stable-0.8. For keeping
compatibility, maybe we should use "-T" for showing elapsed time.

Signed-off-by: Bingpeng Zhu <bingpeng.zbp@alibaba-inc.com>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>