Source json.h non-locally.

Change-Id: Ia42c41fde74596b394a1f7ae0021f1a5510991a8
diff --git a/json-schema.c b/json-schema.c
index 88cc03c..16ddef5 100644
--- a/json-schema.c
+++ b/json-schema.c
@@ -11,7 +11,7 @@
 #include <libgen.h>
 #include <limits.h>
 #include <stdarg.h>
-#include "json.h"
+#include <json.h>
 #include "json-schema.h"
 #include "edk/BaseTypes.h"