message: also cross-test Windows from Linux, macOS
diff: @@ -35,7 +35,13 @@ function run_tests {
  run_tests
  # cross-test 32bit Linux from everywhere
  MIRI_TEST_TARGET=i686-unknown-linux-gnu run_tests
  +
  if [ "$TRAVIS_OS_NAME" == linux ]; then
  # cross-test 64bit macOS from Linux
  FOREIGN_TARGET=x86_64-apple-darwin run_tests
  + # cross-test 32bit Windows from Linux
  + FOREIGN_TARGET=i686-pc-windows-msvc run_tests
  +elif [ "$TRAVIS_OS_NAME" == osx ]; then
  + # cross-test 64bit Windows from macOS
  + FOREIGN_TARGET=x86_64-pc-windows-msvc run_tests
  fi
  