This change overrides ro.postinstall.fstab.prefix to /product, for
cppreopt.rc to use product-specific /product/etc/fstab.postinstall (i.e.
/system/product/etc/fstab.postinstall) to mount system_other partition.
The AVB key is specified in this fstab to mount system_other with
dm-verity.
Bug: 129032485
Test: boot device and checks cppreopt results
init: processing action (ro.postinstall.fstab.prefix=/product && sys.cppreopt=requested) from (/system/etc/init/cppreopts.rc:27)
init: [libfs_avb]Returning avb_handle for '/postinstall' with status: Success
init: [libfs_avb]Built verity table: '1 /dev/block/by-name/system_a /dev/block/by-name/system_a 4096 4096 644999 644999 sha1 c6c7051bf32dbc20623fc5b5b99bad0b27233a0e 25e465b1dc1e8274beea7e4e5f2712f7e1a90e26 10 use_fec_from_device /dev/block/by-name/system_a fec_roots 2 fec_blocks 650080 fec_start 650080 restart_on_corruption ignore_zero_blocks'
Change-Id: I032bfcaaa463f9ab694bf056bf05f551b772980d
