Use line-based list syntax in Build-Depends

Line-based list syntax makes lists easy to extend without creating
commit noise.

src/stub

             echo 'Section: misc'
             echo 'Priority: extra'
             echo 'Standards-Version: 3.9.2'
-            echo 'Build-Depends: debhelper (>= 9)'
+            echo 'Build-Depends:'
+            echo ' debhelper (>= 9),'
             echo ''
             echo 'Package: __MKIT_PROJ_PKGNAME__'
             echo 'Architecture: all'