[PATCH RESEND] zic, various tests: use LFS I/O functions explicitly where needed

[Paul Eggert]

Nick Alcock wrote:
> you are now depending on the
> order of error-checks in the kernel's stat implementation (that it
> returns EOVERFLOW only after it's had the opportunity to return ENOENT,
> so that EOVERFLOW -> !ENOENT)

No, because ENOENT and EOVERFLOW are mutually exclusive regardless of the order 
of error checks, as the stat buffer of a nonexistent file cannot possibly 
overflow. So there is no dependency, and no bug here.

> Maybe I should have fallen back on adding to tz-cflags?

That would be better, in that glibc source would continue to match tzcode 
exactly. It doesn't hurt correctness to compile zic.c with 
-D_FILE_OFFSET_BITS=64, and doing that should make 32-bit zic run a tiny bit 
faster on directories whose inode numbers (or sizes, timestamps, ...) don't fit 
in 32 bits. So it is a tiny performance win even if it is not a bug fix.