I looked at source. Archive has 17M because it contain all objects, binaries, own copies of freetype library etc..
There is a README with info for those crazy people who want to build it which I summary in few words: "hack here, hack there, #define private public so it will build".
In other words - qpdf 2.3.0-snapshot looks like previous release - lots of hacks in includes needed etc stuff. I suspect that noone will be so crazy to try to build it for OZ (atleast not someone from OZ/OE team).