debian: Make the libdpkg-dev package Multi-Arch:same

debian/changelog

@@ -56,6 +56,8 @@ dpkg (1.18.2) UNRELEASED; urgency=low
     - Future-proof tar invocations in Dpkg::Source::Archive for options that
       might become positional in the future, and by always placing function
       options first.
+  * Packaging:
+    - Make the libdpkg-dev package Multi-Arch:same.
   * Documentation:
     - Fix grammar in dpkg-architecture(1).
       Thanks to Chris Lamb <lamby@debian.org>. Closes: #787616

debian/control

@@ -21,6 +21,7 @@ Package: libdpkg-dev
 Section: libdevel
 Priority: optional
 Architecture: any
+Multi-Arch: same
 Depends: zlib1g-dev, liblzma-dev, libbz2-dev, ${misc:Depends}
 Description: Debian package management static library
  This package provides the header files and static library necessary to

debian/dselect.install

@@ -2,7 +2,7 @@
 
 etc/dpkg/dselect.cfg.d
 usr/bin/dselect
-usr/lib/dpkg/methods
+usr/lib/*/dpkg/methods usr/lib/dpkg
 usr/share/locale/*/LC_MESSAGES/dselect.mo
 usr/share/perl5/Dselect
 var/lib/dpkg/methods

debian/libdpkg-dev.install

@@ -1,3 +1,3 @@
 usr/include/dpkg/*.h
-usr/lib/pkgconfig/libdpkg.pc
-usr/lib/libdpkg.a
+usr/lib/*/pkgconfig/libdpkg.pc
+usr/lib/*/libdpkg.a

debian/libdpkg-perl.install

@@ -1,4 +1,4 @@
-usr/lib/dpkg/parsechangelog
+usr/lib/*/dpkg/parsechangelog usr/lib/dpkg
 usr/share/locale/*/LC_MESSAGES/dpkg-dev.mo
 usr/share/man/man3/Dpkg*.3
 usr/share/perl5/Dpkg*

debian/rules

@@ -20,6 +20,7 @@ dpkg_buildflags = \
 DEB_BUILD_GNU_TYPE  ?= $(shell dpkg-architecture -qDEB_BUILD_GNU_TYPE)
 DEB_HOST_GNU_TYPE   ?= $(shell dpkg-architecture -qDEB_HOST_GNU_TYPE)
 DEB_HOST_ARCH_OS    ?= $(shell dpkg-architecture -qDEB_HOST_ARCH_OS)
+DEB_HOST_MULTIARCH  ?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
 
 # Support cross-compiling.
 ifeq ($(DEB_BUILD_GNU_TYPE), $(DEB_HOST_GNU_TYPE))
@@ -54,6 +55,7 @@ build-tree/config.status: configure
 		--infodir=\$${datadir}/info \
 		--sysconfdir=/etc \
 		--sbindir=/sbin \
+		--libdir=\$${prefix}/lib/$(DEB_HOST_MULTIARCH) \
 		--localstatedir=/var \
 		--with-zlib \
 		--with-liblzma \