tracing: Convert local function_graph functions to static

Local functions should be static.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace_functions_graph.c

@@ -353,7 +353,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
 	return ret;
 }
 
-int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
+static int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
 {
 	if (tracing_thresh)
 		return 1;
@@ -442,7 +442,7 @@ void set_graph_array(struct trace_array *tr)
 	smp_mb();
 }
 
-void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
+static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
 {
 	if (tracing_thresh &&
 	    (trace->rettime - trace->calltime < tracing_thresh))
@@ -475,7 +475,7 @@ static void graph_trace_reset(struct trace_array *tr)
 	unregister_ftrace_graph();
 }
 
-int graph_trace_update_thresh(struct trace_array *tr)
+static int graph_trace_update_thresh(struct trace_array *tr)
 {
 	graph_trace_reset(tr);
 	return graph_trace_init(tr);
@@ -1435,7 +1435,7 @@ static void __print_graph_headers_flags(struct seq_file *s, u32 flags)
 	seq_printf(s, "               |   |   |   |\n");
 }
 
-void print_graph_headers(struct seq_file *s)
+static void print_graph_headers(struct seq_file *s)
 {
 	print_graph_headers_flags(s, tracer_flags.val);
 }