The fseek() function on Windows only accepts a 32-bit long offset
argument. Because of this we have our own version, BLI_fseek(), which
will use 64-bit _fseeki64() on Windows. This patch just replaces some
fseek() calls with BLI_fseek().
Differential Revision: https://developer.blender.org/D11430
Reviewed by Brecht Van Lommel