Remove unnecessary use of non-portable 'mkdir()'

[Lubomir I. Ivanov]

On 15 February 2015 at 21:55, Linus Torvalds
<torvalds at linux-foundation.org> wrote:
> This fixes the problem with Windows being the usual non-POSIX PoS that it is..
>
> Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
> ---
> On Sun, Feb 15, 2015 at 11:05 AM, Linus Torvalds
> <torvalds at linux-foundation.org> wrote:
>>
>> So I think the rigth thing to do is to just remove "system_git_dir()"
>> entirely, and replace its use with "system_default_directory()"
>> instead.
>
> Actual tested (now that I got it to build) patch attached.

i guess we can still keep the wrapper i wrote since - if my memory
serves me correctly this is the second time(?) mkdir usage pops out.

[PATCH 2/5] OS: add the subsurface_mkdir() wrapper
it will probably conflict with this patch though, so let me know if i
have to fix mine.

...or just discard the wrapper addition for now, which is fine.

lubomir
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