* sysdeps/unix/sysv/linux/xstatconv.c [STAT_IS_KERNEL_STAT]:
Conditionalize the function definitions on this.
* sysdeps/unix/sysv/linux/xstat.c (__xstat) [STAT_IS_KERNEL_STAT]:
Don't use xstat_conv, just fail if VERS != _STAT_VER_KERNEL.
* sysdeps/unix/sysv/linux/fxstat.c (__fxstat) [STAT_IS_KERNEL_STAT]:
Likewise.
* sysdeps/unix/sysv/linux/lxstat.c (__lxstat) [STAT_IS_KERNEL_STAT]:
Likewise.