fs: xattr_handler table should be const

The entries in xattr handler table should be immutable (ie const)
like other operation tables.

Later patches convert common filesystems. Uncoverted filesystems
will still work, but will generate a compiler warning.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/generic_acl.c b/fs/generic_acl.c
index fe5df54..99800e5 100644
--- a/fs/generic_acl.c
+++ b/fs/generic_acl.c
@@ -201,7 +201,7 @@
 	return -EAGAIN;
 }
 
-struct xattr_handler generic_acl_access_handler = {
+const struct xattr_handler generic_acl_access_handler = {
 	.prefix = POSIX_ACL_XATTR_ACCESS,
 	.flags	= ACL_TYPE_ACCESS,
 	.list	= generic_acl_list,
@@ -209,7 +209,7 @@
 	.set	= generic_acl_set,
 };
 
-struct xattr_handler generic_acl_default_handler = {
+const struct xattr_handler generic_acl_default_handler = {
 	.prefix = POSIX_ACL_XATTR_DEFAULT,
 	.flags	= ACL_TYPE_DEFAULT,
 	.list	= generic_acl_list,