NFS: Fix the selection of security flavours in Kconfig

Randy Dunlap reports:

ERROR: "svc_gss_principal" [fs/nfs/nfs.ko] undefined!


because in fs/nfs/Kconfig, NFS_V4 selects RPCSEC_GSS_KRB5
and/or in fs/nfsd/Kconfig, NFSD_V4 selects RPCSEC_GSS_KRB5.

RPCSEC_GSS_KRB5 does 5 selects, but none of these is enforced/followed
by the fs/nfs[d]/Kconfig configs:

	select SUNRPC_GSS
	select CRYPTO
	select CRYPTO_MD5
	select CRYPTO_DES
	select CRYPTO_CBC

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: J. Bruce Fields <bfields@fieldses.org>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig
index 443c161..3376d76 100644
--- a/net/sunrpc/Kconfig
+++ b/net/sunrpc/Kconfig
@@ -18,10 +18,11 @@
 	  If unsure, say N.
 
 config RPCSEC_GSS_KRB5
-	tristate "Secure RPC: Kerberos V mechanism (EXPERIMENTAL)"
-	depends on SUNRPC && EXPERIMENTAL
+	tristate
+	depends on SUNRPC && CRYPTO
+	prompt "Secure RPC: Kerberos V mechanism" if !(NFS_V4 || NFSD_V4)
+	default y
 	select SUNRPC_GSS
-	select CRYPTO
 	select CRYPTO_MD5
 	select CRYPTO_DES
 	select CRYPTO_CBC
@@ -34,7 +35,7 @@
 	  available from http://linux-nfs.org/.  In addition, user-space
 	  Kerberos support should be installed.
 
-	  If unsure, say N.
+	  If unsure, say Y.
 
 config RPCSEC_GSS_SPKM3
 	tristate "Secure RPC: SPKM3 mechanism (EXPERIMENTAL)"