Update Kotlin to 1.2.20.
Update Kotlin to 1.2.20.

aosp-mirror/platform_frameworks_support,AndroidX/androidx,aosp-mirror/platform_frameworks_support,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx,androidx/androidx,aosp-mirror/platform_frameworks_support,AndroidX/androidx,androidx/androidx,androidx/androidx,aosp-mirror/platform_frameworks_support,androidx/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,aosp-mirror/platform_frameworks_support,AndroidX/androidx