json: Clean up headers

The JSON parser has three public headers, json-lexer.h, json-parser.h,
json-streamer.h.  They all contain stuff that is of no interest
outside qobject/json-*.c.

Collect the public interface in include/qapi/qmp/json-parser.h, and
everything else in qobject/json-parser-int.h.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-54-armbru@redhat.com>

qga/main.c

@@ -18,7 +18,7 @@
 #include <syslog.h>
 #include <sys/wait.h>
 #endif
-#include "qapi/qmp/json-streamer.h"
+#include "qapi/qmp/json-parser.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qjson.h"
 #include "qapi/qmp/qstring.h"