The guys from graphviz seem to have changed their server-layout. The SRC_URL is wrong and need to be fixed. 1.16 works (on AMD64) but is masked in portage.1.11 is not available anymore... New URL: http://www.graphviz.org/pub/graphviz/ARCHIVE/ why I filed this as major ? - a lot apps depend on it ... I noticed some other bugs around this topic but they mentioned 1.10
1.11 is no longer in portage.