WINGs: Make the test examples to compile

Those examples are optional but currently cannot compile properly.
The compiler is reporting some unused variables and missing header file.

WINGs/Tests/testmywidget.c

@@ -4,7 +4,7 @@
 
 #include "mywidget.h"
 
-void wAbort()
+_Noreturn void wAbort(void)
 {
 	exit(1);
 }