Fix unused warnings in perl wrappers

Examples/test-suite/preproc_defined.i

@@ -102,6 +102,7 @@ ANOTHER_MACRO(int)
 void another_macro_checking(void) {
   struct Defined d;
   d.defined = 10;
+  (void)d;
   thing(10);
   stuff(10);
   bumpf(10);

Examples/test-suite/typemap_subst.i

@@ -27,12 +27,14 @@
     (void)c;
     (void)d;
     (void)e;
+    (void)f;
   }
   { /* Test locals */
     basetemp.member = 0;
     startemp = &basetemp;
     temp = &startemp;
     amptemp = &temp;
+    (void)amptemp;
   }
   { /* Test descriptors */
     void *desc = $descriptor;