UBUNTU: [Packaging] do not use compression for image packages

linux-image-ABI packages contain compressed content only (vmlinuz,
changelog) and thus the deb does not benefit at all from being
recompressed again. Only copyring file is compressed. We can actually
avoid shipping /doc/ at all, by symlinking it to the modules package
provided /doc/.

Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

debian/rules.d/2-binary-arch.mk

@@ -605,7 +605,7 @@ binary-%: checks-%
 	dh_testdir
 	dh_testroot
 
-	$(call dh_all,$(pkgimg))
+	$(call dh_all,$(pkgimg)) -- -Znone
 	$(call dh_all,$(pkgimg_mods))
 
 ifeq ($(do_extras_package),true)