[PATCH] stat changes for PPC64

[Roland McGrath]

If powerpc64 will support no struct stat format but the kernel one, then I
don't think it should define _STAT_VER_LINUX and accept it as an alias with
a no-op converter function.  I think kernel_stat.h should not define a
structure at all if it's identical, it can just define a macro
STAT_IS_KERNEL_STAT that is checked in the places that use xstatconv.c so
that they instead just always return EINVAL for any VERS value other than
_STAT_VER_KERNEL.  I have put in your changes with those additional
modifications.  Please let me know if what I've checked in works ok for
you.  Also please notice how I added the canonical level of detail to your
log entries.