Add a name to API level map for O.

O is released, so we don't get this knowledge from the development
codenames list any more.

Test: make ndk # with an API using introduced=O
Bug: None
Change-Id: I21104c5d97c89f2f85157ac7d73de8cd5a478571
diff --git a/android/api_levels.go b/android/api_levels.go
index 370d553..2c4ae1a 100644
--- a/android/api_levels.go
+++ b/android/api_levels.go
@@ -67,6 +67,7 @@
 		"M":     23,
 		"N":     24,
 		"N-MR1": 25,
+		"O":     26,
 	}
 	for i, codename := range ctx.Config().(Config).PlatformVersionCombinedCodenames() {
 		apiLevelsMap[codename] = baseApiLevel + i