fdo#74697 Add Bluez 5 support for impress remote.

This time we:
 - Don't break SAL_WARN with an fprintf like syntax.
 - Replace DBUS_TYPE_UNIX_FD with it's definition 'h' as we might
   be building on dbus-glib versions that do not support it (however
   presumably anyone running bluez 5 will have a dbus version that is
   new enough to support this, i.e. purely a build-time issue).
 - Remove various C++11'isms.

Change-Id: I736cad2122cd3789a5c7fb62c39e409d41fc1e32
Reviewed-on: https://gerrit.libreoffice.org/8924
Tested-by: Andrzej Hunt <andrzej.hunt@collabora.com>
Reviewed-by: Andrzej Hunt <andrzej.hunt@collabora.com>