message: [docker] fix installing emacs, start testing building with android sdk api 24
diff: @@ -24,7 +24,7 @@ RUN apt install -y g++-mingw-w64-x86-64
  RUN apt install -y g++-7
  RUN apt install -y g++-7-multilib
  # For testing and debugging
  -RUN apt install emacs-nox
  +RUN apt install -y emacs-nox
  ENV LIBTORRENT_REVISION="6aad9a463236f0e12f4c4808e4aa84aa0d8b7450"
  ENV BOOST_MAJOR="1"
  @@ -66,7 +66,7 @@ RUN cd /src \
  RUN cd /src \
  && android-ndk/build/tools/make_standalone_toolchain.py --arch arm --api 19 --stl libc++ --install-dir android-toolchain-arm \
  && android-ndk/build/tools/make_standalone_toolchain.py --arch arm64 --api 21 --stl libc++ --install-dir android-toolchain-arm64 \
  - && android-ndk/build/tools/make_standalone_toolchain.py --arch x86 --api 19 --stl libc++ --install-dir android-toolchain-x86 \
  + && android-ndk/build/tools/make_standalone_toolchain.py --arch x86 --api 24 --stl libc++ --install-dir android-toolchain-x86 \
  && android-ndk/build/tools/make_standalone_toolchain.py --arch x86_64 --api 21 --stl libc++ --install-dir android-toolchain-x86_64
  # Build OpenSSL arm
  