Add Xcode 9.2 to the testing support

Fixes #4060

objectivec/DevTools/full_mac_build.sh

diff --git a/objectivec/DevTools/full_mac_build.sh b/objectivec/DevTools/full_mac_build.sh
index 7e1e9a0..b34e28f 100755
--- a/objectivec/DevTools/full_mac_build.sh
+++ b/objectivec/DevTools/full_mac_build.sh
@@ -261,11 +261,11 @@
           -destination "platform=iOS Simulator,name=iPhone 7,OS=latest" # 64bit
       )
       ;;
-    9.[0-1]* )
+    9.[0-2]* )
       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
-          # 9.0/9.1 both seem to often fail running destinations in parallel
+          # 9.0-9.2 all seem to often fail running destinations in parallel
           -disable-concurrent-testing
       )
       ;;