ztest should randomly change recordsize

Improve the large block feature test coverage by extending ztest
to frequently change the recordsize.  This is specificially designed
to catch corner cases which might otherwise go unnoticed.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue openzfs#354

cmd/ztest/ztest.c

@@ -4795,6 +4795,9 @@ ztest_dsl_prop_get_set(ztest_ds_t *zd, uint64_t id)
 		(void) ztest_dsl_prop_set_uint64(zd->zd_name, proplist[p],
 		    ztest_random_dsl_prop(proplist[p]), (int)ztest_random(2));
 
+	VERIFY0(ztest_dsl_prop_set_uint64(zd->zd_name, ZFS_PROP_RECORDSIZE,
+	    ztest_random_blocksize(), (int)ztest_random(2)));
+
 	(void) rw_unlock(&ztest_name_lock);
 }