libzfs: don't distribute libzfs_impl.h

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12048

lib/libzfs/os/linux/libzfs_mount_os.c

@@ -47,7 +47,7 @@
 #include <sys/dsl_crypt.h>
 #include <libzfs.h>
 
-#include "libzfs_impl.h"
+#include "../../libzfs_impl.h"
 #include <thread_pool.h>
 
 #define	ZS_COMMENT	0x00000000	/* comment */

lib/libzfs/os/linux/libzfs_pool_os.c

@@ -49,7 +49,7 @@
 
 #include "zfs_namecheck.h"
 #include "zfs_prop.h"
-#include "libzfs_impl.h"
+#include "../../libzfs_impl.h"
 #include "zfs_comutil.h"
 #include "zfeature_common.h"
 

lib/libzfs/os/linux/libzfs_sendrecv_os.c

@@ -22,7 +22,7 @@
 
 #include <libzfs.h>
 
-#include "libzfs_impl.h"
+#include "../../libzfs_impl.h"
 
 #ifndef F_SETPIPE_SZ
 #define	F_SETPIPE_SZ (F_SETLEASE + 7)

lib/libzfs/os/linux/libzfs_util_os.c

@@ -38,7 +38,7 @@
 #include <libzfs.h>
 #include <libzfs_core.h>
 
-#include "libzfs_impl.h"
+#include "../../libzfs_impl.h"
 #include "zfs_prop.h"
 #include <libzutil.h>
 #include <sys/zfs_sysfs.h>