Remove sdt.h

It's mostly a noop on ZoL and it conflicts with platforms that 
support dtrace.  Remove this header to resolve the conflict.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes #9497

module/os/linux/zfs/zfs_acl.c

@@ -36,7 +36,6 @@
 #include <sys/kmem.h>
 #include <sys/cmn_err.h>
 #include <sys/errno.h>
-#include <sys/sdt.h>
 #include <sys/fs/zfs.h>
 #include <sys/mode.h>
 #include <sys/policy.h>

module/zfs/zfs_ioctl.c

@@ -183,7 +183,6 @@
 #include <sys/zone.h>
 #include <sys/nvpair.h>
 #include <sys/pathname.h>
-#include <sys/sdt.h>
 #include <sys/fs/zfs.h>
 #include <sys/zfs_ctldir.h>
 #include <sys/zfs_dir.h>