Source json.h non-locally.

Change-Id: Ia42c41fde74596b394a1f7ae0021f1a5510991a8
diff --git a/sections/cper-section-firmware.c b/sections/cper-section-firmware.c
index a3c3002..e45015a 100644
--- a/sections/cper-section-firmware.c
+++ b/sections/cper-section-firmware.c
@@ -5,7 +5,7 @@
  * Author: Lawrence.Tang@arm.com
  **/
 #include <stdio.h>
-#include "json.h"
+#include <json.h>
 #include "../edk/Cper.h"
 #include "../cper-utils.h"
 #include "cper-section-firmware.h"