global.h: Use forward-declarations to reduce number of dependencies

src/system/fsmounter.cpp

@@ -36,6 +36,7 @@
 
 #include <system/fsmounter.h>
 #include <cstdlib>
+#include <cstring>
 #include <fstream>
 #include <limits>
 

src/system/httptool.cpp

@@ -18,7 +18,7 @@
 	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA
 */
 
-
+#include <cstring>
 #include <system/httptool.h>
 
 #include <curl/curl.h>
@@ -30,7 +30,6 @@
 
 #include <global.h>
 
-
 CHTTPTool::CHTTPTool()
 {
 	statusViewer = NULL;

src/system/setting_helpers.cpp

@@ -53,6 +53,7 @@
 #include <neutrino.h>
 #include <gui/widget/stringinput.h>
 #include <gui/infoclock.h>
+#include <gui/infoviewer.h>
 #include <driver/volume.h>
 #include <system/helpers.h>
 // obsolete #include <gui/streaminfo.h>