[patch] Document options for building and linking to libstdc++fs.a

[Jonathan Wakely]

On 16/10/15 17:09 +0300, niXman wrote:
>Jonathan Wakely 2015-10-16 16:58:
>>This documents how to use the Filsystem TS library.
>>
>>Committed to trunk.
>
>Hi,
>
>>+      The library implementation
>>+      is incomplete on non-POSIX platforms, specifically Windows 
>>support is
>>+      rudimentary.
>
>I'm at work upon trying to make Filesystem library work for MinGW-W64.

Great! Let me know if you have any questions or if I can help by
adding any abstractions to hide POSIX-specific details.