depends: create a hostid and buildid and add option for salts

These add very simple sanity checks to ensure that the build/host toolchains
have not changed since the last run. If they have, all ids will change and
packages will be rebuilt.

For more complicated usage (like parsing dpkg), HOST_ID_SALT/BUILD_ID_SALT may
be used to introduce arbitrary data to the ids.

depends/funcs.mk

@@ -39,7 +39,7 @@ define int_get_build_id
 $(eval $(1)_dependencies += $($(1)_$(host_arch)_$(host_os)_dependencies) $($(1)_$(host_os)_dependencies))
 $(eval $(1)_all_dependencies:=$(call int_get_all_dependencies,$(1),$($($(1)_type)_native_toolchain) $($(1)_dependencies)))
 $(foreach dep,$($(1)_all_dependencies),$(eval $(1)_build_id_deps+=$(dep)-$($(dep)_version)-$($(dep)_recipe_hash)))
-$(eval $(1)_build_id_long:=$(1)-$($(1)_version)-$($(1)_recipe_hash)-$(release_type) $($(1)_build_id_deps))
+$(eval $(1)_build_id_long:=$(1)-$($(1)_version)-$($(1)_recipe_hash)-$(release_type) $($(1)_build_id_deps) $($($(1)_type)_id_string))
 $(eval $(1)_build_id:=$(shell echo -n "$($(1)_build_id_long)" | $(build_SHA256SUM) | cut -c-$(HASH_LENGTH)))
 final_build_id_long+=$($(package)_build_id_long)