Those kind of functions should be placed in druntime,
but the *64 (v) functions as a public interface are actually
deprecated and shouldn't be used anymore.
Druntime takes care that the normal stat, fopen, calls support
large files, if __USE_FILE_OFFSET64 is defined (which is what
the new C API does as well)
Note: It's actually important to use the functions from
core.sys.posix.stdio as the functions in core.stdc.stdio
are not large file aware. This is probably a bug in druntime.