nfsd: add a new config option for the block layout driver

Split the config symbols into a generic pNFS one, which is invisible
and gets selected by the layout drivers, and one for the block layout
driver.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/Makefile b/fs/nfsd/Makefile
index 9a6028e..679cdc6 100644
--- a/fs/nfsd/Makefile
+++ b/fs/nfsd/Makefile
@@ -17,4 +17,5 @@
 nfsd-$(CONFIG_NFSD_V3_ACL) += nfs3acl.o
 nfsd-$(CONFIG_NFSD_V4)	+= nfs4proc.o nfs4xdr.o nfs4state.o nfs4idmap.o \
 			   nfs4acl.o nfs4callback.o nfs4recover.o
-nfsd-$(CONFIG_NFSD_PNFS) += nfs4layouts.o blocklayout.o blocklayoutxdr.o
+nfsd-$(CONFIG_NFSD_PNFS) += nfs4layouts.o
+nfsd-$(CONFIG_NFSD_BLOCKLAYOUT) += blocklayout.o blocklayoutxdr.o