* scripts/controllib.pl (get_host_arch): New function.

	* scripts/controllib.pl (get_host_arch): New function.
	(findarch): Rename to ...
	(init_substvar_arch): ... this. Use get_host_arch to set the substvar.
	Fix all callers.
	(parsedep): Use get_host_arch instead of directly calling
	dpkg-architecture.
	* scripts/dpkg-genchanges.pl: Use '$host_arch' instead of '$arch'.
	(init_substvar_arch): Delay call until after init_substvars.
	* scripts/dpkg-gencontrol.pl: Likewise.