CIFS: Add new mount option to set owner uid and gid from special sids in acl

Add "idsfromsid" mount option to indicate to cifs.ko that it should
try to retrieve the uid and gid owner fields from special sids in the
ACL if present.  This first patch just adds the parsing for the mount
option.

Signed-off-by: Steve French <steve.french@primarydata.com>
Reviewed-by:  Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 0c828d3..1f17f6b 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -478,6 +478,7 @@ struct smb_vol {
 	bool retry:1;
 	bool intr:1;
 	bool setuids:1;
+	bool setuidfromacl:1;
 	bool override_uid:1;
 	bool override_gid:1;
 	bool dynperm:1;