Use #pragma once

#pragma once is safer and simpler. According to Wikipedia it's supported by all major compilers.

include/yajl_utils.h

@@ -7,8 +7,7 @@
  * yajl_utils.h
  *
  */
-#ifndef I3_YAJL_UTILS_H
-#define I3_YAJL_UTILS_H
+#pragma once
 
 #include <yajl/yajl_gen.h>
 #include <yajl/yajl_parse.h>
@@ -27,5 +26,3 @@ typedef size_t ylength;
 #define yalloc(callbacks, client) yajl_alloc(callbacks, NULL, NULL, client)
 typedef unsigned int ylength;
 #endif
-
-#endif