knfsd: nfsd4: build rpcsec_gss whenever nfsd4 is built

Select rpcsec_gss support whenever asked for NFSv4 support.  The rfc actually
requires gss, and gss is also the main reason to migrate to v4.  We already do
this on the client side.
Signed-off-by: N"J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/Kconfig

@@ -1675,6 +1675,7 @@ config NFSD_V3_ACL
 config NFSD_V4
 	bool "Provide NFSv4 server support (EXPERIMENTAL)"
 	depends on NFSD_V3 && EXPERIMENTAL
+	select RPCSEC_GSS_KRB5
 	help
 	  If you would like to include the NFSv4 server as well as the NFSv2
 	  and NFSv3 servers, say Y here.  This feature is experimental, and