new tmpfiles-d.eclass (v2)

Second attempt to bring basic tmpfiles.d support to the tree.

The first one:
http://www.mail-archive.com/gentoo-dev <at> lists.gentoo.org/msg52059.html

Changed since:

- eclass tmpfilesd.eclass renamed to tmpfiles-d.eclass
- {do,new}tmpfilesd renamed to {do,new}tmpfiles_d
- systemd.eclass now uses tmpfiles-d.eclass as it was
  the donor of one of functions:
 systemd_dotmpfilesd() {
        debug-print-function ${FUNCNAME} "${ <at> }"

-       (
-               insinto /usr/lib/tmpfiles.d/
-               doins "${ <at> }"
-       )
+       dotmpfiles_d "${ <at> }"
 }

I've found only one user of systemd_dotmpfilesd:
media-sound/teamspeak-server-bin which can be just
converted to use shorter wrapper if needed.

And systemd ebuild does the same by hands (i guess
can be converted):
        # Create /run/lock as required by new baselay/OpenRC compat.
        insinto /usr/lib/tmpfiles.d
        doins "${FILESDIR}"/gentoo-run.conf