Separate warning for incomplete and corrupt streams

This change adds a separate return code to zfs_ioc_recv that is used 
for incomplete streams, in addition to the existing return code for 
streams that contain corruption.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes #10122

include/sys/fs/zfs.h

@@ -1330,6 +1330,7 @@ typedef enum {
 	ZFS_ERR_UNKNOWN_SEND_STREAM_FEATURE,
 	ZFS_ERR_EXPORT_IN_PROGRESS,
 	ZFS_ERR_BOOKMARK_SOURCE_NOT_ANCESTOR,
+	ZFS_ERR_STREAM_TRUNCATED,
 } zfs_errno_t;
 
 /*