[Telepathy] Announce: telepathy-mission-control 5.12.3

[Simon McVittie]

The "put it with the other Kryptonite" release.

tarball:
http://telepathy.freedesktop.org/releases/telepathy-mission-control/telepathy-mission-control-5.12.3.tar.gz
signature:
http://telepathy.freedesktop.org/releases/telepathy-mission-control/telepathy-mission-control-5.12.3.tar.gz.asc

Fixes:

• Recover from incomplete password migrations caused by upgrading to
  Empathy 3 while running MC 5.12.1 or older, by deleting the old (MC)
  copy of the password if Empathy has already copied it (fd.o #42088,
  Simon)
• Omit generated file mcp-signals-marshal.h from tarballs (Simon)
• Fix distcheck in out-of-tree builds (Simon)
• Backport a patch from 5.13.1 to make the gnome-keyring regression test
  work with modern gnome-keyring (Simon)