Fix various mismatched prototypes and other compilation problems.

Core (make cpc) builds again, but crashes on startup.
diff --git a/contiki/apps/processes-dsc.c b/contiki/apps/processes-dsc.c
index 7315828..e2c37df 100644
--- a/contiki/apps/processes-dsc.c
+++ b/contiki/apps/processes-dsc.c
@@ -35,7 +35,6 @@
 
 #include "dsc.h"
 
-extern struct ctk_icon processes_icon;
 /*-----------------------------------------------------------------------------------*/
 DSC(processes_dsc,
     "Process information",
@@ -70,5 +69,7 @@
 #if CTK_CONF_ICONS
 static struct ctk_icon processes_icon =
   {CTK_ICON("Processes", processesicon_bitmap, processesicon_textmap)};
+#else
+extern struct ctk_icon processes_icon;
 #endif /* CTK_CONF_ICONS */
 /*-----------------------------------------------------------------------------------*/