changed iscsi_data.size from int to size_t

iscsi_data.size is used as parameter to memory
operation functions (such as malloc) which except
size_t rather than int.

Signed-off-by: Peter Lieven <pl@kamp.de>

include/iscsi.h

@@ -573,7 +573,7 @@ iscsi_task_mgmt_target_cold_reset_async(struct iscsi_context *iscsi,
  */
 
 struct iscsi_data {
-       int size;
+       size_t size;
        unsigned char *data;
 };