scripts/mk: Set DEB_TARGET_ variables from architecture.mk

Missed in commit f29ed62d0c340869752c61d55a2df74159c31625.

debian/changelog

@@ -20,6 +20,8 @@ dpkg (1.17.17) UNRELEASED; urgency=low
     - Allow multiple whitespace in Dpkg::BuildProfiles::get_build_profiles()
       when parsing the DEB_BUILD_PROFILES environment variable.
       Thanks to Johannes Schauer <j.schauer@email.de>.
+  * Set the DEB_TARGET_* dpkg-architecture variables from architecture.mk.
+    Missed in dpkg 1.17.14.
 
   [ Updated programs translations ]
   * German (Sven Joachim).

scripts/mk/architecture.mk

@@ -6,6 +6,6 @@ dpkg_late_eval ?= $(or $(value DPKG_CACHE_$(1)),$(eval DPKG_CACHE_$(1) := $(shel
 
 dpkg_architecture_setvar = $(1) ?= $(call dpkg_late_eval,$(1),dpkg-architecture -q$(1))
 
-$(foreach machine,BUILD HOST,\
+$(foreach machine,BUILD HOST TARGET,\
   $(foreach var,ARCH ARCH_OS ARCH_CPU ARCH_BITS ARCH_ENDIAN GNU_CPU GNU_SYSTEM GNU_TYPE MULTIARCH,\
     $(eval $(call dpkg_architecture_setvar,DEB_$(machine)_$(var)))))