Missing forward declarations in DSCs.

Makes gcc5 happy.
diff --git a/contiki/apps/about-dsc.c b/contiki/apps/about-dsc.c
index 9a3fdc4..436d304 100644
--- a/contiki/apps/about-dsc.c
+++ b/contiki/apps/about-dsc.c
@@ -35,6 +35,7 @@
 
 #include "dsc.h"
 
+static const struct ctk_icon about_icon;
 /*-----------------------------------------------------------------------------------*/
 const DSC(about_dsc,
     "About Contiki",
diff --git a/contiki/apps/calc-dsc.c b/contiki/apps/calc-dsc.c
index b6f96a4..6456c8e 100644
--- a/contiki/apps/calc-dsc.c
+++ b/contiki/apps/calc-dsc.c
@@ -35,6 +35,7 @@
 
 #include "dsc.h"
 
+static const struct ctk_icon calc_icon;
 /*-----------------------------------------------------------------------------------*/
 const DSC(calc_dsc,
     "Simple calculator",
diff --git a/contiki/apps/editor-dsc.c b/contiki/apps/editor-dsc.c
index 76ba196..ded221e 100644
--- a/contiki/apps/editor-dsc.c
+++ b/contiki/apps/editor-dsc.c
@@ -35,6 +35,7 @@
 
 #include "dsc.h"
 
+static const struct ctk_icon editor_icon;
 /*-----------------------------------------------------------------------------------*/
 const DSC(editor_dsc,
     "A simple text editor",
diff --git a/contiki/apps/netconf-dsc.c b/contiki/apps/netconf-dsc.c
index 8ed4766..49585e8 100644
--- a/contiki/apps/netconf-dsc.c
+++ b/contiki/apps/netconf-dsc.c
@@ -35,6 +35,7 @@
 
 #include "dsc.h"
 
+static const struct ctk_icon netconf_icon;
 /*-----------------------------------------------------------------------------------*/
 const DSC(netconf_dsc,
     "Network configuration",
diff --git a/contiki/apps/processes-dsc.c b/contiki/apps/processes-dsc.c
index 8966d5f..17a98e4 100644
--- a/contiki/apps/processes-dsc.c
+++ b/contiki/apps/processes-dsc.c
@@ -35,6 +35,7 @@
 
 #include "dsc.h"
 
+static const struct ctk_icon processes_icon;
 /*-----------------------------------------------------------------------------------*/
 const DSC(processes_dsc,
     "Process information",
diff --git a/contiki/apps/shell-dsc.c b/contiki/apps/shell-dsc.c
index 5868589..c23194f 100644
--- a/contiki/apps/shell-dsc.c
+++ b/contiki/apps/shell-dsc.c
@@ -35,6 +35,7 @@
 
 #include "dsc.h"
 
+static const struct ctk_icon shell_icon;
 /*-----------------------------------------------------------------------------------*/
 const DSC(shell_dsc,
     "The Contiki command shell",