Exclude REL from preview API levels.

Bug: http://b/156513478#comment43
Test: m ndk # barbet-next-userdebug in goog/main
Change-Id: I0ff1e45d61d605493c784a118232b839324e066e

android/config.go

@@ -1003,12 +1003,18 @@ func (c *config) FinalApiLevels() []ApiLevel {
 
 func (c *config) PreviewApiLevels() []ApiLevel {
 	var levels []ApiLevel
-	for i, codename := range c.PlatformVersionActiveCodenames() {
+	i := 0
+	for _, codename := range c.PlatformVersionActiveCodenames() {
+		if codename == "REL" {
+			continue
+		}
+
 		levels = append(levels, ApiLevel{
 			value:     codename,
 			number:    i,
 			isPreview: true,
 		})
+		i++
 	}
 	return levels
 }