see https://bugs.gentoo.org/show_bug.cgi?id=525560
%bcond_with system_mesa # system Mesa
%bcond_without system_minizip # system minizip
%bcond_without system_opus # system opus codec support, http://www.opus-codec.org/examples/
-%bcond_without system_protobuf # system protobuf
+# protobuf broken: https://bugs.gentoo.org/show_bug.cgi?id=525560
+%bcond_with system_protobuf # system protobuf
%bcond_without system_re2 # system re2
%bcond_without system_snappy # system snappy
%bcond_without system_speex # system speex