Isolated emscripten in new lib

lib/emscripten/emtests/test_longjmp_throw.cpp

@@ -0,0 +1,43 @@
+// Copyright 2014 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>
+#include <setjmp.h>
+
+static jmp_buf buf;
+volatile int x = 0;
+
+void second(void) {
+  printf("second\n");
+  if (x == 17) throw 5;
+  else longjmp(buf, -1);
+}
+
+void first(void) {
+  printf("first\n");
+  longjmp(buf, 1);
+}
+
+int main() {
+  int jmpval = setjmp(buf);
+  if (!jmpval) {
+    x++;
+    first();
+    printf("skipped\n");
+  } else if (jmpval == 1) {
+    printf("result: %d %d\n", x, jmpval);
+    x++;
+    try {
+      second();
+    } catch(int a) {
+      x--;
+      second();
+    }
+  } else if (jmpval == -1) {
+    printf("result: %d %d\n", x, jmpval);
+  }
+
+  return 0;
+}