Constant naughtyfy::flags::FAN_MARK_IGNORE

pub const FAN_MARK_IGNORE: u32 = 0x00000400;

This bit is mutually exclusive with FAN_MARK_IGNORED_MASK bit. When using FAN_MARK_IGNORE for the first time, mark starts using independent event flags in ignore mask. After that, trying to update the ignore mask with the old FAN_MARK_IGNORED_MASK API will result in EEXIST error.