[PATCH 2 of 2] dirstate: normalize on case insensitive filesystems on Mac (issue1663)

[timeless]

mpm wrote:
> There may also be some interesting non-folding forms of mangling but
> none spring to mind.

do these count as interesting?
c:\progra~1 or the NTFS version which was something like c:\Prxxxx~1
yielding c:\program files

c:\programf
HKLM\System\CurrentControlSet\Control\FileSystem\NameNumericTail

http://technet.microsoft.com/en-us/library/cc751487.aspx
http://blogs.msdn.com/oldnewthing/archive/2004/04/14/113052.aspx