Isolated emscripten in new lib

lib/emscripten/emtests/test_stack_byval.c

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2016 The Emscripten Authors.  All rights reserved.
+ * Emscripten is available under two separate licenses, the MIT license and the
+ * University of Illinois/NCSA Open Source License.  Both these licenses can be
+ * found in the LICENSE file.
+ */
+
+// We should also not blow up the stack with byval arguments
+#include <stdio.h>
+struct vec {
+  int x, y, z;
+  vec(int x_, int y_, int z_) : x(x_), y(y_), z(z_) {}
+  static vec add(vec a, vec b) { return vec(a.x + b.x, a.y + b.y, a.z + b.z); }
+};
+int main() {
+  int total = 0;
+  for (int i = 0; i < 1000; i++) {
+    for (int j = 0; j < 1000; j++) {
+      vec c(i + i % 10, j * 2, i % 255);
+      vec d(j * 2, j % 255, i % 120);
+      vec f = vec::add(c, d);
+      total += (f.x + f.y + f.z) % 100;
+      total %= 10240;
+    }
+  }
+  printf("sum:%d*\n", total);
+  return 0;
+}