ovl: Add S_CASEFOLD as part of the inode flag to be copied

ovl: Add S_CASEFOLD as part of the inode flag to be copied

To keep ovl's inodes consistent with their real inodes, create a new
mask for inode file attributes that needs to be copied.  Add the
S_CASEFOLD flag as part of the flags that need to be copied along with
the other file attributes.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: André Almeida <andrealmeid@igalia.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>