[dcl.attr.nodiscard] Fix vexing-parse bug in example. Make sure the

missiles actually get launched, not merely redeclared.

Author: zygoloid

source/declarations.tex

@@ -9050,7 +9050,7 @@
 void launch_missiles();
 void test_missiles() {
   my_scopeguard();              // warning encouraged
-  void(my_scopeguard()),        // warning not encouraged, cast to \tcode{void}
+  (void)my_scopeguard(),        // warning not encouraged, cast to \tcode{void}
     launch_missiles();          // comma operator, statement continues
   my_unique(42);                // warning encouraged
   my_unique();                  // warning not encouraged