experiment: actually enable experiments when using -all

Ooops.

diff --git a/experiment/experiment.go b/experiment/experiment.go
index e7c798a..90546eb 100644
--- a/experiment/experiment.go
+++ b/experiment/experiment.go
@@ -115,7 +115,8 @@
 		e.Enabled = true
 	}
 	if byName["all"].Enabled {
-		for _, e := range experiments {
+		for i := range experiments {
+			e := &experiments[i]
 			if e.Name == "list" {
 				continue
 			}