Add the Product ID to target_files.zip
Add the Product ID to target_files.zip

When using the A/B updater, include the product id string to
target_files.zip.
This is needed by the Omaha backend.

Bug: 24946811
Change-Id: I2ce5f6cffe440c29a1820348ee215c71cec07861

xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build