Make graph_next_line() available in the graph.h API

In order to successfully use the graph API from a context other than the
stdout/command-line scenario (where the graph_show_* functions are
suitable), we need direct access to graph_next_line(), to drive the
graph drawing process.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

graph.c

@@ -7,17 +7,6 @@
 
 /* Internal API */
 
-/*
- * Output the next line for a graph.
- * This formats the next graph line into the specified strbuf.  It is not
- * terminated with a newline.
- *
- * Returns 1 if the line includes the current commit, and 0 otherwise.
- * graph_next_line() will return 1 exactly once for each time
- * graph_update() is called.
- */
-static int graph_next_line(struct git_graph *graph, struct strbuf *sb);
-
 /*
  * Output a padding line in the graph.
  * This is similar to graph_next_line().  However, it is guaranteed to
@@ -1143,7 +1132,7 @@ static void graph_output_collapsing_line(struct git_graph *graph, struct strbuf
 		graph_update_state(graph, GRAPH_PADDING);
 }
 
-static int graph_next_line(struct git_graph *graph, struct strbuf *sb)
+int graph_next_line(struct git_graph *graph, struct strbuf *sb)
 {
 	switch (graph->state) {
 	case GRAPH_PADDING:

graph.h

@@ -32,6 +32,17 @@ void graph_update(struct git_graph *graph, struct commit *commit);
  */
 int graph_is_commit_finished(struct git_graph const *graph);
 
+/*
+ * Output the next line for a graph.
+ * This formats the next graph line into the specified strbuf.  It is not
+ * terminated with a newline.
+ *
+ * Returns 1 if the line includes the current commit, and 0 otherwise.
+ * graph_next_line() will return 1 exactly once for each time
+ * graph_update() is called.
+ */
+int graph_next_line(struct git_graph *graph, struct strbuf *sb);
+
 
 /*
  * graph_show_*: helper functions for printing to stdout