smpp_mirror is maintained in osmo-msc.git, so let's remove it
(and the associated libsmpp34 build requirement).
Change-Id: Ia7b242cc52cf261b1a5dd3c287da2868e1a2b9a8
This is the first step in creating this repository from the legacy openbsc.git.
Like all other Osmocom repositories, keep the autoconf and automake files in
the repository root. openbsc.git has been the sole exception, which ends now.
Change-Id: I9c6f2a448d9cb1cc088cf1cf6918b69d7e69b4e7