* debian/control: remvove build-dep on clang.
* Sync many things from debian:
  - No longer build remoting, or install its locale files.
  - Use many system libraries, adding build-dep on
      - libre2-dev,
      - yasm,
      - libopus-dev,
      - zlib1g-dev,
      - libspeex-dev,
      - libexpat1-dev,
      - libpng12-dev,
      - libxml2-dev,
      - libjpeg-turbo8-dev | libjpeg9-dev,
      - libwebp-dev,
      - libxslt1-dev,
      - libsrtp0-dev,
      - libjsoncpp-dev,
      - libevent1-dev,
      - libharfbuzz-dev,
  - Clean up many parts of debian/rules, wrt variable names
  - Set hardening on.
  - Use gold linker.
  - Disable Google Now. Creepy. Might mean downloads of opaque programs too.
  - Disable Wallet service.