omni: Fix backuptool for Q

* ro.omni.version is now in product
* Edit 69-gapps.sh for new app and symlink. It's created by GAPPS installer.sh

Change-Id: I269e40247217bd41b94c0d5363da93532143d43e
diff --git a/prebuilt/common/bin/backuptool_ab.sh b/prebuilt/common/bin/backuptool_ab.sh
index b96c594..edf472f 100755
--- a/prebuilt/common/bin/backuptool_ab.sh
+++ b/prebuilt/common/bin/backuptool_ab.sh
@@ -50,7 +50,7 @@
     return 0
 fi
 
-grep -q "^ro.omni.version=$V.*" /system/etc/prop.default /system/build.prop && return 1
+grep -q "^ro.omni.version=$V.*" /product/build.prop && return 1
 
 echo "Not backing up files from incompatible version: $V"
 return 0