SUNRPC/NFS: Add Kbuild dependencies for NFS_DEBUG/RPC_DEBUG

This allows us to turn on/off the dprintk() debugging interfaces for
those distributions that don't ship the 'rpcdebug' utility.
It also allows us to add Kbuild dependencies. Specifically, we already
know that dprintk() in general relies on CONFIG_SYSCTL. Now it turns out
that the NFS dprintks depend on CONFIG_CRC32 after we added support
for the filehandle hash.

Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
index 7bce64c..2a0e6c5 100644
--- a/fs/nfs/Kconfig
+++ b/fs/nfs/Kconfig
@@ -144,3 +144,9 @@
 	depends on NFS_V4 && !NFS_USE_LEGACY_DNS
 	select DNS_RESOLVER
 	default y
+
+config NFS_DEBUG
+	bool
+	depends on NFS_FS && SUNRPC_DEBUG
+	select CRC32
+	default y