The system/vendor/product read only partitions will be moved
to fstab.ro.system file to easily identify them in the future.
Bug: 356425337
Test: $ source build/envsetup.sh
$ lunch [zumapro]-trunk_staging-userdebug
$ m
$ ./vendor/google/tools/flashall -w
Flag: EXEMPT bugfix
Change-Id: I0402df991160e1fabdfdc5d4e4482320f671ae09
