replace framebuffer.h include with forward declaration

instead of including framebuffer.h almost everywhere, replace it with
class CFrameBuffer forward declarations and/or generic system includes.
Add a hack to define fb_pixel_t to config.h (one reason for
framebuffer.h includes was the fb_pixel_t define)


Origin commit data
------------------
Branch: ni/coolstream
Commit: 63b6efd1f5
Author: Stefan Seyfried <seife@tuxbox-git.slipkontur.de>
Date: 2017-02-05 (Sun, 05 Feb 2017)



------------------
This commit was generated by Migit

src/system/helpers.cpp

@@ -49,6 +49,7 @@
 #include "debug.h"
 #include <global.h>
 #include <driver/fontrenderer.h>
+#include <driver/framebuffer.h>
 #include <system/helpers.h>
 #include <gui/update_ext.h>
 using namespace std;

src/system/httptool.cpp

@@ -18,6 +18,7 @@
 	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA
 */
 
+#include <config.h>
 #include <cstring>
 #include <system/httptool.h>