pnfs-obj: objlayoutdriver module skeleton

* Define the PNFS_OBJLAYOUT Kconfig option in the nfs
  master Kconfig file.
* Add the objlayout driver to the Kernel's Kbuild system.
* Add the fs/nfs/objlayout/Kbuild file for building the
  objlayoutdriver.ko driver
* Define fs/nfs/objlayout/objio_osd.c, register the driver on module
  initialization and unregister on exit.

[pnfs-obj: remove of CONFIG_PNFS fallout]
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
[added "unsure" clause]
[depend on NFS_V4_1]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
diff --git a/fs/nfs/Makefile b/fs/nfs/Makefile
index 7516a8a..6a34f7d 100644
--- a/fs/nfs/Makefile
+++ b/fs/nfs/Makefile
@@ -21,3 +21,5 @@
 
 obj-$(CONFIG_PNFS_FILE_LAYOUT) += nfs_layout_nfsv41_files.o
 nfs_layout_nfsv41_files-y := nfs4filelayout.o nfs4filelayoutdev.o
+
+obj-$(CONFIG_PNFS_OBJLAYOUT) += objlayout/