Disable droiddoc for leanback support lib.
Disable droiddoc for leanback support lib.

Bug: 13191130
Change-Id: Id062250a57036a03dceb159b397c898ee5acabdc

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