Adjust stat width calculations to take --graph output into account

Adjust stat width calculations to take --graph output into account

The recent change to compute the width of diff --stat did not take into
consideration the output from --graph. The consequence is that when both
options are used, e.g. in 'log --stat --graph', the lines are too long.

Adjust stat width calculations to take --graph output into account.

Signed-off-by: Lucian Poston <redacted>
Signed-off-by: Junio C Hamano <redacted>