(svn r8300) -Codechange: Add a prototype for DrawPlayerIcon to players.h and include that

instead of using externs. Also move DrawPlayerIcon from graph_gui.cpp to
players.cpp.

src/graph_gui.cpp

@@ -216,11 +216,6 @@ static void DrawGraph(const GraphDrawer *gw)
 /* GRAPH LEGEND */
 /****************/
 
-void DrawPlayerIcon(PlayerID p, int x, int y)
-{
-	DrawSprite(0x2EB, PLAYER_SPRITE_COLOR(p), x, y);
-}
-
 static void GraphLegendWndProc(Window *w, WindowEvent *e)
 {
 	const Player* p;