Added missing loop cancel for Emscripten in test programs.

test/testrendercopyex.c

@@ -152,6 +152,11 @@ void loop()
             continue;
         Draw(&drawstates[i]);
     }
+#ifdef __EMSCRIPTEN__
+    if (done) {
+        emscripten_cancel_main_loop();
+    }
+#endif
 }
 
 int