This also adds comprehensive tests for utimens on regular files,
directories (RHBZ#761451), named pipes (RHBZ#761460), symbolic links,
block and char devices.
Note that there is a small change in the (previously undefined)
semantics of this call: It now sets the time on a symbolic link
itself, not on what the symbolic link points to.
You don't need to open the file O_WRONLY in order to call futimens on
the file descriptor. Opening it O_WRONLY fails for directories.
Therefore open O_RDONLY instead.
Instead of checking for futimens support and falling back
(incorrectly in one case) to using futimes, use gnulib's
module.
However the gnulib module does not yet support Win32, so
this change is only really useful on platforms like RHEL 5.
truncate, truncate_size: Used to truncate files to a particular
size, or to zero bytes.
mkdir_mode: Like mkdir but allows you to also specify the
initial permissions for the new directory.
utimens: Set timestamp on a file with nanosecond accuracy.
lchown: Corresponding to lchown(2) syscall (we already have chown).
The implementation is complicated by the fact that we had to
add an Int64 parameter type to the generator.
