Export its header (mounts.h) from there, and drop the dot dot dependency
from libupdater / updater.
Test: mmma bootable/recovery
Test: recovery_component_test
Change-Id: Ic26a6b9b78a34dbe1f178b138f3abaafffbec44c
find_mounted_volume_by_device() and remount_read_only() have no active
users. And we don't have a code logic that requires these two functions.
Test: mmma bootable/recovery
Test: Code search shows no user.
Change-Id: Ib11c2ba93ee087ea020c1337eb06686a6165f894
