cleanup: add defines for default pareto or zipf values

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/options.c b/options.c
index 12ff621..ab6e399 100644
--- a/options.c
+++ b/options.c
@@ -715,9 +715,9 @@
 		return 0;
 
 	if (td->o.random_distribution == FIO_RAND_DIST_ZIPF)
-		val = 1.1;
+		val = FIO_DEF_ZIPF;
 	else if (td->o.random_distribution == FIO_RAND_DIST_PARETO)
-		val = 0.2;
+		val = FIO_DEF_PARETO;
 	else
 		return 0;