LU-11436 build: always dist debian stuff

Always try to dist debian stuff, so that even on non-dpkg-using
build targets (RHEL series), the tar dist will contain all debian
stuff, and can be delivered to users who want to build lustre on
debian series servers.

Test-Parameters: trivial
Change-Id: I8493f5a5e65078c0160c5493efee6906c87db6f1
Signed-off-by: Gu Zheng <gzheng@ddn.com>
Reviewed-on: https://review.whamcloud.com/33246


Reviewed-by: Wang Shilong <wshilong@ddn.com>
Tested-by: Jenkins
Reviewed-by: Nathaniel Clark <nclark@whamcloud.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Li Dongyang <dongyangli@ddn.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>