missing init scripts in xen-4.10 builds (CONFIG_LINUX=y)

This issue is unique to xen-4.10.

xendriverdomains and xen-watchdog init scripts are never generated or installed in (pkg) xen-utils-common. If the binary-indep rule is run separately as,

fakeroot debian/rules binary-indep

those init scripts should get configured and installed in our package. I've traced this to a missing config flag (CONFIG_LINUX=y), which is also pivotal to configuration and install of systemd support.