Rework transformZExtICmp
Carefully enable optimizations of logic ops on icmps
CheerpBackend: Make it possible to invalidate functions in Registerize
CheerpBackend: Compute live ranges for alloca in Registerize
CheerpBackend: Invalidate the registerize pass in AllocaArrays
CheerpBackend: Split AllocaMerging in two passes and use Registerize in them