UBUNTU: [Packaging] disable zfs module checks when zfs is disabled

We currently disable the zfs module changes when we disable zfs
builds as part of cross-compilation.  We should disable the zfs
module checks whenever zfs itself is disabled.

Pull the zfs module disablement support such that it is always
present.

BugLink: http://bugs.launchpad.net/bugs/1737176Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

debian/rules

@@ -41,7 +41,6 @@ ifneq ($(DEB_HOST_ARCH),$(DEB_BUILD_ARCH))
 	do_tools=false
 	disable_d_i=true
 	do_zfs=false
-	do_zfs_disable:=$(shell cat $(DROOT)/zfs-modules.ignore >>$(prev_abidir)/../modules.ignore)
 endif
 
 # Stages -- support both DEB_STAGE=stage1 and DEB_BUILD_PROFILE=bootstrap
@@ -77,6 +76,10 @@ ifneq ($(do_tools),true)
 	do_tools_common=
 endif
 
+ifeq ($(do_zfs),false)
+	do_zfs_disable:=$(shell cat $(DROOT)/zfs-modules.ignore >>$(prev_abidir)/../modules.ignore)
+endif
+
 # Either tools package needs the common source preparation
 do_any_tools=$(sort $(filter-out false,$(do_linux_tools) $(do_cloud_tools)))