Minor Description
Similar to AVRO-1295 but for the C library. Namespace "" should be the NULL namespace when the schema is parsed. For example this breaks:
```
{"type": "record", "name": "R", "fields": [
{"name": "s", "type": {"type": "record", "namespace": "x", "name": "Y", "fields": [
{"name": "e", "type": {"type": "record", "namespace": "", "name": "Z", "fields": [
]}}
]}},
]}
```
