* sysdeps/unix/sysv/linux/xstatconv.c (xstat_conv): Readd
__unused[1-3] since they're needed by some platforms. Handle
_HAVE_STAT_NSEC and _HAVE_STAT_NSEC64.
* sysdeps/unix/sysv/linux/x86_64/bits/stat.h: Add nsec resolution
for structs stat and stat64.
* sysdeps/unix/sysv/linux/ia64/bits/stat.h: Likewise.
* sysdeps/unix/sysv/linux/powerpc/bits/stat.h: Likewise.
* sysdeps/unix/sysv/linux/sparc/bits/stat.h: Likewise.
* sysdeps/unix/sysv/linux/s390/bits/stat.h: Likewise.