[cc2-qbe] Fix the type in alloc assignation
[cc2-qbe] Fix the type in alloc assignation

The type in this assignation is not the type of the base code,
it is the type of the pointer in the current architecture,
that in our case is the type ptrtype.

k0gaMSX/scc,k0gaMSX/scc,k0gaMSX/scc