nilfs2: make nilfs_sc_*_ops static

This kills the following sparse warnings:

fs/nilfs2/segment.c:567:28: warning: symbol 'nilfs_sc_file_ops' was not declared. Should it be static?
fs/nilfs2/segment.c:617:28: warning: symbol 'nilfs_sc_dat_ops' was not declared. Should it be static?
fs/nilfs2/segment.c:625:28: warning: symbol 'nilfs_sc_dsync_ops' was not declared. Should it be static?

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

fs/nilfs2/segment.c

diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 8b4e280..c920164 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -564,7 +564,7 @@
 	*vblocknr = binfo->bi_v.bi_vblocknr;
 }
 
-struct nilfs_sc_operations nilfs_sc_file_ops = {
+static struct nilfs_sc_operations nilfs_sc_file_ops = {
 	.collect_data = nilfs_collect_file_data,
 	.collect_node = nilfs_collect_file_node,
 	.collect_bmap = nilfs_collect_file_bmap,
@@ -614,7 +614,7 @@
 	*binfo_dat = binfo->bi_dat;
 }
 
-struct nilfs_sc_operations nilfs_sc_dat_ops = {
+static struct nilfs_sc_operations nilfs_sc_dat_ops = {
 	.collect_data = nilfs_collect_dat_data,
 	.collect_node = nilfs_collect_file_node,
 	.collect_bmap = nilfs_collect_dat_bmap,
@@ -622,7 +622,7 @@
 	.write_node_binfo = nilfs_write_dat_node_binfo,
 };
 
-struct nilfs_sc_operations nilfs_sc_dsync_ops = {
+static struct nilfs_sc_operations nilfs_sc_dsync_ops = {
 	.collect_data = nilfs_collect_file_data,
 	.collect_node = NULL,
 	.collect_bmap = NULL,