Squash upstream commits up to and including the v1.6.8
release (upstream commit 1cad15cc).

This repository's changes from upstream are now limited to:

- addition of Android.mk, CleanSpec.mk, config.h, and NOTICE
  files
- addition of dbus/dbus-arch-deps.h and removal from
  dbus/.gitignore (ebae2d21, f022f55d)
- WANT_PIDFILE #ifdefs added to bus/bus.c to disable writing
  dbus-daemon's PID to a file (3100d06a)
- TRACE_LOCKS set to 0 in dbus/dbus-connection.c (88a0ffe5)
- DBUS_ANDROID_LOG added to dbus/dbus-internals.c to use
  logcat (7de15def)
- ANDROID_MANAGED_SOCKET added to dbus/dbus-sysdeps-unix.c
  to use an SELinux-managed socket rather than a
  dbus-daemon-created Unix domain socket (3100d06a)

Bug: 22328216
Change-Id: I793ebdf963d9b0740f0da28f1de593d088f08406