Adaptions for API change in json-c v0.13

Lift restriction on json-c <= 0.12.1

ipc-server: Acquire ownership of referenced json_object properly

When adding a referenced json_object with an unknown lifetime to
another json_object, it must be done with a wrapped call to
json_object_get() to acquire the ownership of that json_object.

include/sway_json_helper.h

@@ -0,0 +1,16 @@
+#ifndef _SWAY_JSON_HELPER_H
+#define _SWAY_JSON_HELPER_H
+
+#include <json-c/json.h>
+
+// Macros for checking a specific version.
+#define JSON_C_VERSION_013 (13 << 8)
+
+// json-c v0.13 uses size_t for array_list_length().
+#if defined(JSON_C_VERSION_NUM) && JSON_C_VERSION_NUM >= JSON_C_VERSION_013
+typedef size_t json_ar_len_t;
+#else
+typedef int json_ar_len_t;
+#endif
+
+#endif // _SWAY_JSON_HELPER_H

include/swaygrab/json.h

@@ -1,4 +1,4 @@
-#include <json-c/json.h>
+#include "sway_json_helper.h"
 #include "wlc/wlc.h"
 
 void init_json_tree(int socketfd);