Fix #4453: Avoid adding type bindings in getVariables

[nicolasstucki]

getVariables is used when desugaring val/var/lazy val pat = e but after other errors
pat may contain a type name.

[abgruszecki]

LGTM. Today I Learned that var bindings can be destructuring and this is perfectly legal code:

var Some(z) = Some(0)

By the way, that definition seems to put current master into an infinite loop and this commit fixes that as well :)

EDIT: scratch that, I just double checked if master actually chokes on that definition to see if maybe we shouldn't add it as a test. Turns out it does not, must've been something weird going on in my environment which was fixed when I switched branches and cleaned everything.