replace fontrenderer.h include with forward declaration

in order to flatten the build dependency tree further, include
fontrenderer.h directly where needed, in header files a forward
declaration is enough


Origin commit data
------------------
Commit: 9082ddf287
Author: Stefan Seyfried <seife@tuxbox-git.slipkontur.de>
Date: 2017-02-05 (Sun, 05 Feb 2017)

src/gui/components/cc_frm_button.cpp

@@ -32,6 +32,7 @@
 #include <gui/color_custom.h>
 #include <system/debug.h>
 #include "cc_frm_button.h"
+#include <driver/fontrenderer.h>
 
 using namespace std;
 

src/gui/components/cc_frm_clock.cpp

@@ -36,6 +36,7 @@
 #include <ctype.h>
 #include <system/helpers.h>
 #include <system/debug.h>
+#include <driver/fontrenderer.h>
 
 using namespace std;
 

src/gui/components/cc_frm_ext_text.cpp

@@ -28,6 +28,7 @@
 #include <global.h>
 #include <neutrino.h>
 #include "cc_frm_ext_text.h"
+#include <driver/fontrenderer.h>
 
 #include <sigc++/bind.h>
 

src/gui/components/cc_frm_footer.cpp

@@ -29,6 +29,7 @@
 #include <gui/color_custom.h>
 #include "cc_frm_footer.h"
 #include <system/debug.h>
+#include <driver/fontrenderer.h>
 
 using namespace std;
 

src/gui/components/cc_frm_header.cpp

@@ -30,6 +30,7 @@
 #include <neutrino.h>
 #include "cc_frm_header.h"
 #include <system/debug.h>
+#include <driver/fontrenderer.h>
 
 #include <sigc++/bind.h>
 

src/gui/components/cc_frm_signalbars.cpp

@@ -30,6 +30,7 @@
 #include <global.h>
 #include <neutrino.h>
 #include "cc_frm_signalbars.h"
+#include <driver/fontrenderer.h>
 #include <sstream>
 
 #define SB_MIN_HEIGHT 12

src/gui/components/cc_item_text.cpp

@@ -31,6 +31,7 @@
 #include <global.h>
 #include <neutrino.h>
 #include "cc_item_text.h"
+#include <driver/fontrenderer.h>
 #include <sstream>
 #include <fstream>
 #include <errno.h>

src/gui/components/cc_types.h

@@ -27,11 +27,11 @@
 #define __CC_TYPES__
 
 #include <system/localize.h>
-#include <driver/fontrenderer.h>
 #include <driver/rcinput.h>
 #include <gui/color_custom.h>
 
 struct gradientData_t;
+class Font;
 class CComponentsForm;
 class CComponentsScrollBar;