[sgen] Fix bridge interop missing some xrefs due to improve registration.

	* sgen-bridge.c: Split the registration and dfs1 steps so we avoid issues
	where an earlier entry that points to a later one would not have a xref
	created between them.

	First we insert all bridges into the hash table and then we do dfs1.

	It must be done in 2 steps since the bridge arrays doesn't come in reverse topological order,
	which means that we can have entry N pointing to entry N + 1.

	If we dfs1 entry N before N + 1 is registered we'll not consider N + 1 for this bridge
	pass and not create the required xref between the two.