fs_mgr: overlayfs takes const std::vector<const fstab_rec*>&

fs_mgr_overlayfs_mount_all() and fs_mgr_overlayfs_required_devices()
to also take const std::vector<const fstab_rec*>& argument.

Bug: 117933812
Test: manual adb-remount-test.sh
Change-Id: Ic72fcca1fe32c311ff3f903c7275e6f7dfba46a7
2 files changed