core: use syscall wrappers instead of direct syscalls - tail(2)

core: use syscall wrappers instead of direct syscalls - tail(2)

tail, as in dog chasing its tail. These are the unwrapped
syscalls that have crept in (or were missed) in the previous
patches.

various xlators and other components are invoking system calls
directly instead of using the libglusterfs/syscall.[ch] wrappers.

If not using the system call wrappers there should be a comment
in the source explaining why the wrapper isn't used.

Change-Id: I6015f97109c4250a5a049496a214d19835e4ae19
BUG: 1267967
Signed-off-by: Kaleb S KEITHLEY <kkeithle@redhat.com>
Reviewed-on: http://review.gluster.org/12590
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>