libyang CHANGE review header includes

The plugins_types.h was supposed only for implementing data type plugins
code, so I've removed it from libyang.h (now it is supposed to be
included explicitly).
diff --git a/src/json.c b/src/json.c
index d7bf050..56bf734 100644
--- a/src/json.c
+++ b/src/json.c
@@ -15,13 +15,13 @@
 #include <assert.h>
 #include <ctype.h>
 #include <errno.h>
-#include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/types.h>
 
 #include "common.h"
-#include "json.h"
 #include "in_internal.h"
+#include "json.h"
 
 #define JSON_PUSH_STATUS_RET(CTX, STATUS) \
     LY_CHECK_RET(ly_set_add(&CTX->status, (void*)STATUS, 1, NULL))