AST: Fix WhereClauseOwner::getLoc() and simple_display() for DifferentiableAttr
AST: Fix WhereClauseOwner::getLoc() and simple_display() for DifferentiableAttr

We forgot to handle this case, which would lead to a crash.

apple/swift,gregomni/swift,rudkx/swift,roambotics/swift,glessard/swift,benlangmuir/swift,gregomni/swift,roambotics/swift,apple/swift,glessard/swift,ahoppen/swift,benlangmuir/swift,glessard/swift,roambotics/swift,ahoppen/swift,glessard/swift,gregomni/swift,atrick/swift,JGiola/swift,atrick/swift,benlangmuir/swift,gregomni/swift,gregomni/swift,roambotics/swift,benlangmuir/swift,rudkx/swift,benlangmuir/swift,apple/swift,glessard/swift,roambotics/swift,gregomni/swift,JGiola/swift,roambotics/swift,JGiola/swift,ahoppen/swift,apple/swift,JGiola/swift,ahoppen/swift,ahoppen/swift,apple/swift,rudkx/swift,apple/swift,atrick/swift,atrick/swift,rudkx/swift,benlangmuir/swift,glessard/swift,ahoppen/swift,atrick/swift,JGiola/swift,atrick/swift,rudkx/swift,JGiola/swift,rudkx/swift