this helps to keep the build rule simpler, and easier to customize
* -j$(NUMJOBS) is taken care of by 'dh --parallel'
* use 'autoreconf' dh add-on to autoconf cleanup
* add dh-autoreconf to Build-Depends
* bump debhelper compatibility level to 8, as jewel's supported
debian based distro is jessie (with debhelper 9.20150101),
ubuntu trusty (with debhelper 9.20131227ubuntu1)
Signed-off-by: Kefu Chai <kchai@redhat.com>