message: Travis: updated Vulkan SDK version to 1.2.154.0; enabled downloading the SDK for both iOS and Mac builds.
diff: CMAKE_VERSION="3.18.2"
  -VULKAN_SDK_VER="1.2.135.0"
  +VULKAN_SDK_VER="1.2.154.0"
  if [ "$TRAVIS_OS_NAME" = "osx" ]; then
  wget --no-check-certificate https://github.com/Kitware/CMake/releases/download/v${CMAKE_VERSION}/cmake-${CMAKE_VERSION}-Darwin-x86_64.tar.gz &&
  tar -xzf cmake-${CMAKE_VERSION}-Darwin-x86_64.tar.gz
  export PATH=$PWD/cmake-${CMAKE_VERSION}-Darwin-x86_64/CMake.app/Contents/bin:$PATH
  cmake --version
  - if [ "$IOS" = "true" ]; then
  + # Download Vulkan SDK
  wget -O vulkansdk-macos-$VULKAN_SDK_VER.tar.gz https://sdk.lunarg.com/sdk/download/$VULKAN_SDK_VER/mac/vulkansdk-macos-$VULKAN_SDK_VER.tar.gz?Human=true &&
  tar -xzf vulkansdk-macos-$VULKAN_SDK_VER.tar.gz
  export VULKAN_SDK=$PWD/vulkansdk-macos-$VULKAN_SDK_VER
  fi
  -fi
  if [ "$TRAVIS_OS_NAME" = "linux" ]; then
  # Link gcc-9 and g++-9 to their standard commands
  