Build qcow2 images for non-SUBARCH core images for lxd purposes.

live-build/auto/build

@@ -37,6 +37,11 @@ if [ "${IMAGEFORMAT:-}" = "ubuntu-image" ] \
 		#  we should be supporting more than one for models that
 		#  define those.
 		mv output/*.img "$PREFIX".img
+		# For standard, non-platform-specific core images, prepare a
+		# qcow2 image as well for LXD consumption.
+		if [ -z "${SUBARCH:-}" ]; then
+			convert_to_qcow2 "$PREFIX".img "$PREFIX".qcow2 ;;
+		fi
 		xz -0 -T4 "$PREFIX".img
 		mv output/seed.manifest "$PREFIX".manifest