spa_json_init assumes that we start in an object and always requires a
key/value pair. If the last part is a key, it returns and error and does
not want to return the key value.
This causes problems when parsing AUX0,AUX1,AUX2 or any relaxed array
withand odd number of elements.
Make a new spa_json_init_relax that takes the type of the container
we're assuming we're in and set the state of the parser to array when we
are parsing a relaxed array.
Fixes#4944
94d0d8bc09