Supporting ext4 case-insensitive directories

[Gabriel Ivăncescu]

Hi,

With the latest kernel release candidate, ext4 received support for 
native case-insensitivity on a per-directory basis. This is done using 
the EXT2_IOC_SETFLAGS ioctl and the EXT4_CASEFOLD_FL flag (and GETFLAGS 
to retrieve it) for a given directory. Note that it works only on empty 
directories.

I'll add support for it, and retrieving it should not be a problem to 
add in Wine. However my question now is: should Wine, by default, 
attempt to create the 'drive_c' directory with this attribute on (on new 
prefixes)? Do we want to do that?

Thankfully we don't need to apply it to other directories, because 
according to: https://github.com/torvalds/linux/blob/master/fs/ext4/ext4.h

EXT4_FL_INHERITED contains EXT4_CASEFOLD_FL, so it is inherited on new 
subdirectories automatically. This means we really only need to set it 
when creating drive_c itself.

Thoughts?