Merge buildd-bootable/bionic into ubuntu/bionic

Backports to enable building of bootable buildd images LP: #1863024

MP: https://code.launchpad.net/~davidkrauser/livecd-rootfs/+git/livecd-rootfs/+merge/380908

live-build/auto/config

@@ -150,8 +150,10 @@ case $IMAGEFORMAT in
 				COMPONENTS='main restricted universe multiverse'
 				;;
 			*)
-				case $PROJECT in
-					ubuntu-cpc)
+				case $PROJECT:${SUBPROJECT:-} in
+					ubuntu-base:buildd)
+						;;
+					ubuntu-cpc:*)
 						;;
 					*)
 						add_package live jasper

live-build/buildd/hooks/49-empty-resolv-conf.binary

@@ -1,4 +1,3 @@
-#!/bin/sh
-set -e
-
-chroot chroot truncate -s 0 /etc/resolv.conf
+#!/bin/sh -e
+chroot chroot rm /etc/resolv.conf
+chroot chroot touch /etc/resolv.conf

live-build/buildd/hooks/50-buildd-tar.binary

@@ -6,5 +6,5 @@ set -e
 
 # gzip was chosen for fastest decompression speed: it decompresses buildd
 # chroots about twice as fast as xz and about five times as fast as bzip2.
-tar --transform='s,^binary,chroot-autobuild,' --sort=name --numeric-owner \
-	-czf "livecd.$PROJECT.rootfs.tar.gz" binary
+tar --transform='s,^chroot,chroot-autobuild,' --sort=name --numeric-owner \
+	-czf "livecd.$PROJECT.rootfs.tar.gz" chroot

live-build/buildd/hooks/51-buildd-lxd.binary

@@ -11,6 +11,6 @@ tar --numeric-owner -cf "livecd.$PROJECT.lxd.tar" -C "$TMPDIR" metadata.yaml
 rm -rf "$TMPDIR"
 # When using the combined metadata/rootfs form, the rootfs must be under
 # rootfs/ rather than under chroot-autobuild/.
-tar --transform='s,^binary,rootfs,' --sort=name --numeric-owner \
-	-rf "livecd.$PROJECT.lxd.tar" binary
+tar --transform='s,^chroot,rootfs,' --sort=name --numeric-owner \
+	-rf "livecd.$PROJECT.lxd.tar" chroot
 gzip -9 "livecd.$PROJECT.lxd.tar"