Don't save ScrollView/HorizontalScrollView saved state for old apps

Older apps may have given IDs to ScrollViews and views of a different
class in layouts that vary by configuration. Now that ScrollViews save
state this causes ClassCastExceptions when trying to restore instance
state.

Only save new instance state for ScrollView/HorizontalScrollView for
apps targeting post-API 18.

Change-Id: Icaa095cd20bef35dddc225a17c5a8e30b3faea02