rbd/write_same: make it compatible with lower version of librbd
More detail please see:
/*
* rbd_aio_writesame support was added in librbd 1.12.0
*/
-#if LIBRBD_VERSION_CODE >= LIBRBD_VERSION(1, 12, 0)
+#if LIBRBD_VERSION_CODE >= LIBRBD_VERSION(1, 12, 0) || LIBRBD_SUPPORTS_WRITESAME
#define RBD_WRITE_SAME_SUPPORT
#endif
