Reduce size of git-favicon.png using a combination of optipng and
pngout. From 164 bytes to 115 bytes (30% reduction). Also reduce
git-logo.png's size by one byte using advcomp.
Signed-off-by: Benjamin Kramer <benny.kra@googlemail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>