Add Xcode 9 support to the helper script.

objectivec/DevTools/full_mac_build.sh

@@ -279,6 +279,12 @@ if [[ "${DO_XCODE_IOS_TESTS}" == "yes" ]] ; then
           -destination "platform=iOS Simulator,name=iPhone 7,OS=latest" # 64bit
       )
       ;;
+    9.0* )
+      XCODEBUILD_TEST_BASE_IOS+=(
+          -destination "platform=iOS Simulator,name=iPhone 4s,OS=8.1" # 32bit
+          -destination "platform=iOS Simulator,name=iPhone 7,OS=latest" # 64bit
+      )
+      ;;
     * )
       echo "Time to update the simulator targets for Xcode ${XCODE_VERSION}"
       exit 2