fix compilation with gcc-4.7 by including unistd.h

Origin commit data
------------------
Commit: 4009fea6d8
Author: Stefan Seyfried <seife@tuxbox-git.slipkontur.de>
Date: 2012-10-06 (Sat, 06 Oct 2012)

src/gui/keybind_setup.cpp

@@ -33,6 +33,8 @@
 #include <config.h>
 #endif
 
+#include <unistd.h>
+
 #ifdef HAVE_COOLSTREAM_NEVIS_IR_H
 /* define constants instead of #ifdef'ing the corresponding code.
  * the compiler will optimize it away anyway, but the syntax is

src/gui/network_service.cpp

@@ -24,6 +24,7 @@
 #include <config.h>
 #endif
 
+#include <unistd.h>
 #include <global.h>
 #include <neutrino.h>
 

src/gui/osdlang_setup.cpp

@@ -33,6 +33,7 @@
 #include <config.h>
 #endif
 
+#include <unistd.h>
 
 #include "osdlang_setup.h"