Changes

debian-stretch-titan: use dpkg to install libfftranscode

For some magic reason, apt segfaults while installing the DEBs:

  $ apt install ./libfftranscode0_0.3_${DPKG_ARCH}.deb \
                ./libfftranscode-dev_0.3_${DPKG_ARCH}.deb
  WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
  Reading package lists...
  Segmentation fault (core dumped)

so it kind of confirms the warning about its stability ;)

Change-Id: I7f3288161577b055145afe89de7dff50853760f5