perhaps this is a little pre-mature (i.e. wait until 2.0.17 goes stable) but i noticed that there is this code in the php.eclass: if use gd-external; then myconf="${myconf} --with-gd=/usr" REQUIREPNG=1 starting with 2.0.17, xpm, jpeg, png, and freetype are all optional
please re-open once 2.0.17 is ready for stable.