BLI_winstuff.h redefined fseek/ftell and friends to their 64 bit variants, which made it
impossible to include windows.h (or any of the other windows headers) after BLI_winstuff.h

This fixes all the instances of ftell/fseek/lseek after the inclusion of BLI_winstuff.h
by providing BLI_ variants of these functions that are always 64 bit.

There may be other uses of fseek/ftell but they did not include winstuff previously
and were using 32 bit file IO and hence suspect to breakage, and are still suspect (but
easier to find now, but fixing that is beyond the scope of this diff)

I left in the macro's I used to locate the code that needed updating, so it's a little
more clear why I changed some instances of fseek/tell but not others, this will naturally be
removed before commit.

This diff is required before D6811 can land