pretty: pass graph width to pretty formatting for use in '%>|(N)'

pretty: pass graph width to pretty formatting for use in '%>|(N)'

Pass graph width to pretty formatting, to make N in '%>|(N)'
include columns consumed by graph rendered when --graph option
is in use.

For example, in the output of

  git log --all --graph --pretty='format: [%>|(20)%h] %ar%d'

this change will make all commit hashes align at 20th column from
the edge of the terminal, not from the edge of the graph.

Signed-off-by: Josef Kufner <redacted>
Signed-off-by: Junio C Hamano <redacted>
Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
Signed-off-by: Junio C Hamano <redacted>