Extra declaration of deleted autogen routines

[Thierry Delisle]

Given a struct that can't be assigned, i.e.:

struct Fi {
	int i;
};
struct Fi ?=?(struct Fi &, struct Fi) = void;

struct Fo {
	struct Fi fi;
};

In this example, the resolver will attempt to resolve the assignment operator for Fo and fail to resolved it. It will then mark that operator as deleted, which means code gen will skip it.

However, this process does not remove any forward declaration of the autogenerated routine. This results in a warning of the form : "warning: ‘_X16_operator_assignFS2Fo_S2FoS2Fo_autogen_1’ declared ‘static’ but never defined [-Wunused-function]"