Isolated emscripten in new lib

lib/emscripten/emtests/test_bitfields.c

@@ -0,0 +1,27 @@
+/*
+ * 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.
+ */
+
+#include <stdio.h>
+struct bitty {
+  unsigned x : 1;
+  unsigned y : 1;
+  unsigned z : 1;
+};
+int main() {
+  bitty b;
+  printf("*");
+  for (int i = 0; i <= 1; i++)
+    for (int j = 0; j <= 1; j++)
+      for (int k = 0; k <= 1; k++) {
+        b.x = i;
+        b.y = j;
+        b.z = k;
+        printf("%d,%d,%d,", b.x, b.y, b.z);
+      }
+  printf("*\n");
+  return 0;
+}