Skip tests for (invalid) input with multiple oneof values when Jansson is earlier than version 2.8.
Skip tests for (invalid) input with multiple oneof values when Jansson is earlier than version 2.8.

Behavior in that case can only be guaranteed from Jansson 2.8 on because earlier versions did not iterate over JSON object keys in a deterministic order, causing the test to randomly fail.

Sannis/protobuf2json-c,Sannis/protobuf2json-c,Sannis/protobuf2json-c