Integer values should not be printed using format specifier '%g' which leads to inexact display in case of higher values.

Before this patch:
  -trans_color       <int>        .D.V..... color value [...] (default 1.67772e+07)

Afterwards:
  -trans_color       <int>        .D.V..... color value [...] (default 16777215)
Signed-off-by: softworkz <softworkz@hotmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>