_out/plugin/png/GCC-Gcc-Gui-Linux-Nogtk-Posix-Shared/png.a(pngupp.o): In function `Upp::PNGRaster::Init()': pngupp.cpp:(.text._ZN3Upp9PNGRaster4InitEv+0x2d): undefined reference to `png_create_read_struct' pngupp.cpp:(.text._ZN3Upp9PNGRaster4InitEv+0x64): undefined reference to `png_create_info_struct'
-lpng \