Disable checksum generation

These checksums are unused, integrity checking in launchpad is performed
separately.

debian/changelog

@@ -2,6 +2,7 @@ livecd-rootfs (2.533) UNRELEASED; urgency=medium
 
   [ Robert C Jennings ]
   * ubuntu-cpc: Remove git-man for minimized images 
+  * Disable checksum generation
 
   [ Colin Watson ]
   * live-build/auto/config: Drop "lp-*" hostname filter for Launchpad

live-build/auto/config

@@ -795,6 +795,7 @@ lb config noauto \
 	--initsystem none \
 	--bootloader "$BOOTLOADER" \
 	${INITRAMFS_COMPRESSION:+--initramfs-compression "$INITRAMFS_COMPRESSION"} \
+	--checksums none \
 	--cache false \
 	${BOOTAPPEND_LIVE:+--bootappend-live "$BOOTAPPEND_LIVE"} \
 	$OPTS \