json-streamer: add handling for JSON_ERROR token/state

json-streamer: add handling for JSON_ERROR token/state

This allows a JSON_ERROR state to be passed to the streamer to force a
flush of the current tokens and pass a NULL token list to the parser
rather that have it churn on bad data. (Alternatively we could just not
pass it to the parser at all, but it may be useful to push there errors
up the stack. NULL token lists are not currently handled by the parser,
the next patch will address that)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>