Make sure count() includes unset fields with defaults.
Make sure count() includes unset fields with defaults.

These will appear in a seq of the map, so they should be included
in the count (and otherwise equality is broken and asymmetrical).

l0st3d/clojure-protobuf,oliyh/clojure-protobuf,ninjudd/clojure-protobuf,flatland/clojure-protobuf