message: Missed some 21e->21bs.
diff: if [[ $TRAVIS_OS_NAME == "windows" ]]
  then
  echo "Setting up Android NDK"
  - if [[ ! -d "$HOME/android-ndk-r21e/platforms" ]]
  + if [[ ! -d "$HOME/android-ndk-r21b/platforms" ]]
  then
  echo "Downloading Android NDK"
  wget -q https://dl.google.com/android/repository/android-ndk-r21b-windows-x86_64.zip
  - 7z x android-ndk-r21e-windows-x86_64.zip "-o$HOME/"
  - rm android-ndk-r21e-windows-x86_64.zip
  + 7z x android-ndk-r21b-windows-x86_64.zip "-o$HOME/"
  + rm android-ndk-r21b-windows-x86_64.zip
  else
  echo "Using Android NDK from Travis Cache"
  fi
  