added CHUNK_INITIALIZER

Source/charon/types.c

@@ -38,3 +38,4 @@ mapping_t status_m[] = {
 	{MAPPING_END, NULL}
 };
 
+chunk_t CHUNK_INITIALIZER = {NULL,0};

Source/charon/types.h

@@ -61,6 +61,8 @@ struct chunk_s {
     size_t len;
 };
 
+extern chunk_t CHUNK_INITIALIZER;
+
 /**
  * General purpose boolean type
  */