Add the product version to target_files.zip.
Add the product version to target_files.zip.

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

BUG: 24743570
Change-Id: Idaba06624c1de452b1e1f9d3ebec851229af987a

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