Put product_id and product_version to OEM partition.

Also create symlinks for each entry in /etc/os-release.d to its corresponding
location in /oem/os-release.d.

Test: m installclean && m droid oem_image dist
Bug: 32555385
Bug: 33211225
Bug: 35804180

(cherry picked from commit 8de8ac139aa289f22f5326af2805a64c0b6bd410)
(cherry picked from commit 4c6f2be8720829eaf8681bcf584f1064e735fa7c)
1 file changed