message: Use the proper domain for the key
diff: @@ -11,7 +11,7 @@ CXX_VERSION=5.0.2
  if [ "$KOKORO_BUILD_ID" ]; then
  sudo ln -s /usr/include/x86_64-linux-gnu/asm /usr/include/asm
  - sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 15CF4D18AF4F7421
  + sudo apt-key adv --keyserver apt.llvm.org --recv-keys 15CF4D18AF4F7421
  sudo apt-add-repository "deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-$CLANG_VERSION main"
  sudo apt-get update -y
  sudo apt-get --assume-yes --force-yes install clang-$CLANG_VERSION
  