On Fri, Aug 30, 2013 at 11:57 AM, Keith Marshall <keithmarshall@users.sourceforge.net> wrote:
More details on _FILE_OFFSET_BITS=64 here:

That's specific to Linux, and therefore completely irrelevant for MinGW.
Until it's ratified by the GCC folks upstream, it remains uncertain how
LFS will be activated for the Win32 platform; _FILE_OFFSET_BITS may, or
may not be applicable.

_FILE_OFFSET_BITS=64 is already implemented and working in mingw-w64-based compilers, I've been using this feature for a year and a half. 

Pau Garcia i Quiles
(Due to my workload, I may need 10 days to answer)