media-gfx/graphviz needs -lpng14 in order to build, but the dependency is >=media-libs/libpng-1.4, which pulls in too new libpng. The 1.4 has its own slot, so the dependency needs to be changed to media-libs/libpng:1.4 so the right libs are pulled in. Furthermore, it seems even if the right libs are installed, configure scripts need to be tweaked, because they find 1.5 if it's installed, like on my box, and then it fails too. -lpng14 linker flags are hardcoded in Makefiles BTW. Reproducible: Always
*** This bug has been marked as a duplicate of bug 319101 ***