deb-pkg: Add automatic support for s390x architecture

The Debian s390x architecture has 64-bit userland whereas s390 has
32-bit userland.  A 64-bit kernel can be used with either.  Now that
Debian supports multiarch and officially supports s390x, it makes more
sense to assign a 64-bit kernel package to s390x.
Reported-by: Stephen Powell <zlinuxman@wowway.com>
References: https://bugs.debian.org/750925Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/package/builddeb

@@ -35,7 +35,7 @@ create_package() {
 	sparc*)
 		debarch=sparc ;;
 	s390*)
-		debarch=s390 ;;
+		debarch=s390$(grep -q CONFIG_64BIT=y $KCONFIG_CONFIG && echo x || true) ;;
 	ppc*)
 		debarch=powerpc ;;
 	parisc*)