Look for SDKs 9.0 and 8.4, too

Change-Id: I9cfb2f2a456ab64ffd12c2a4a2a0bfe65507a05e

configure.ac

@@ -3029,7 +3029,7 @@ if test $_os = iOS; then
     xcode_developer=`xcode-select -print-path`
 
     current_sdk_ver=8.3
-    for sdkver in 8.3 8.2 8.1 8.0; do
+    for sdkver in 9.0 8.4 8.3 8.2 8.1 8.0; do
         t=$xcode_developer/Platforms/$platform.platform/Developer/SDKs/$platform$sdkver.sdk
         if test -d $t; then
             ios_sdk=$sdkver