More fix for bug #8159072 Spinner widget should be RTL'ized

- fix DrawableContainerState.getChangingConfigurations() to take care about its children
- make Resources.verifyPreloadConfig() return false when the changing configuration
contains layout direction bits (this is when a Drawable is having different version
for LTR and RTL layout directions)
- use constant state instead of the resource type value for checking if we can
preload the drawable
- fix typo

Change-Id: Idd64caf0fbe0f5cfd5ffe09343e84bafa9446ea5