consistent naming: s/system-wide L2ARC/shared L2ARC/

module/zfs/dbuf.c

@@ -3299,7 +3299,7 @@ dbuf_prefetch_indirect_done(zio_t *zio, const zbookmark_phys_t *zb,
 		} else {
 			ASSERT3U(BP_GET_LSIZE(zio->io_bp), ==, zio->io_size);
 		}
-		/* XXX: with system-wide l2arc, this ASSERT is incorrect.
+		/* XXX: with shared l2arc, this ASSERT is incorrect.
 		 * After conversation with Paul Dagnelie, who added it,
 		 * we concluded that it's not necessary.
 		 * The stack trace was :

module/zfs/spa.c

@@ -1986,7 +1986,7 @@ spa_load_l2cache(spa_t *spa)
 				/*
 				 * Ensure that vdev_is_dead() returns true, so
 				 * we don't l2arc_add_vdev below. The whole
-				 * system-wide L2ARC code relies on this.
+				 * Shared L2ARC code relies on this.
 				 */
 				VERIFY(vdev_is_dead(vd));
 			}