Remove an unused function, mark a bunch of other functions and variables
as static.  Mostly found by sparse.
diff --git a/treesource.c b/treesource.c
index ee0a7b8..14e9e27 100644
--- a/treesource.c
+++ b/treesource.c
@@ -91,7 +91,7 @@
 }
 
 
-void write_tree_source_node(FILE *f, struct node *tree, int level)
+static void write_tree_source_node(FILE *f, struct node *tree, int level)
 {
 	struct property *prop;
 	struct node *child;