Dirt and coarse dirt do not properly use their "snowy" states

Dirt and coarse dirt do not set "snowy" to true when there is snow above them. This is strange as podzol does set the state, and the states exists in the debug world.

The main reason this is a problem (other than the behavior being inconsistant) is because when using multipart on a model to define a separate model for that state (basically to change the texture of dirt when snow is above it), it never shows in game despite the conditions being correct and the state/model existing.