While hack/make.sh checks for systemd headers using pkg-config, we
forgot to ensure that they were there in the images that we use for
building binaries for RPM-based distributions. Add the right packages
to the generate.sh that we use for them, and update the copies of the
generated files that we carry in the source tree.
Notes: Fedora, CentOS, and Oracle Linux put the pkg-config command in
the "pkgconfig" package, while OpenSUSE calls the package "pkg-config".
The systemd-devel package, like systemd, is not in Oracle Linux 6.
Signed-off-by: Nalin Dahyabhai <nalin@redhat.com>