[HarfBuzz] Using snprintf under MSVC

[Behdad Esfahbod]

Thanks.  Pushed a similar fix.

On 15-03-31 02:12 PM, Jonathan Kew wrote:
> Hi Behdad,
> 
> When compiling with MSVC, we have "#define snprintf _snprintf" in
> hb-private.hh. However, it seems that MSVC 2015 now provides snprintf itself,
> so I think we should use that directly instead, and make the #define
> conditional on the value of _MSC_VER.
> 
> (See patch 9 in https://bugzilla.mozilla.org/show_bug.cgi?id=1119776.)
> 
> Thanks,
> 
> JK
> 
>