[CIFS] DNS name resolution helper upcall for cifs

	Adds additional option CIFS_DFS_UPCALL to fs/Kconfig for enabling
        DFS support.  Resolved IP address is saved as a string in the
	key payload.

	Igor has a series of related patches that will follow which finish up
	CIFS DFS support

Acked-by: Igor Mammedov <niallain@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/Makefile b/fs/cifs/Makefile
index 45e42fb..09898b8 100644
--- a/fs/cifs/Makefile
+++ b/fs/cifs/Makefile
@@ -9,3 +9,5 @@
 	  readdir.o ioctl.o sess.o export.o cifsacl.o
 
 cifs-$(CONFIG_CIFS_UPCALL) += cifs_spnego.o
+
+cifs-$(CONFIG_CIFS_DFS_UPCALL) += dns_resolve.o