ovl: make fsync after metadata copy-up opt-in mount option
ovl: fix wrong detection of 32bit inode numbers
ovl: relax requirement for uuid=off,index=on
ovl: make sure that ovl_create_real() returns a hashed dentry
ovl: Support mounting case-insensitive enabled layers
ovl: Check for casefold consistency when creating new dentries
ovl: Add S_CASEFOLD as part of the inode flag to be copied
ovl: Set case-insensitive dentry operations for ovl sb