overlay: workaround libmount failure to remount,ro

overlay: workaround libmount failure to remount,ro

libmount >= v1.39 calls several unneeded fsconfig() calls to reconfigure
lowerdir/upperdir when user requests only -o remount,ro.

Those calls fail because overlayfs does not allow making any config
changes with new mount api, besides MS_RDONLY.

We workaround this problem with --options-mode ignore.

Reported-by: André Almeida <andrealmeid@igalia.com>
Suggested-by: Karel Zak <kzak@redhat.com>
Link: https://lore.kernel.org/linux-fsdevel/20250521-ovl_ro-v1-1-2350b1493d94@igalia.com/
Link: https://lore.kernel.org/fstests/CAJfpegtJ3SDKmC80B4AfWiC3JmtWdW2+78fRZVtsuhe-wSRPvg@mail.gmail.com/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>