BUG: fix python3/2 numpy import_array macro build issue with clang

Author: cpcloud

pandas/src/ujson/python/objToJSON.c

@@ -100,7 +100,7 @@ enum PANDAS_FORMAT
 //#define PRINTMARK() fprintf(stderr, "%s: MARK(%d)\n", __FILE__, __LINE__)
 #define PRINTMARK()
 
-#if (PY_VERSION_HEX >= 0x03000000)
+#if (PY_VERSION_HEX < 0x03000000)
 void initObjToJSON(void)
 #else
 int initObjToJSON(void)