Isolated emscripten in new lib

lib/emscripten/emtests/test_fast_math.c

@@ -0,0 +1,20 @@
+/*
+ * 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>
+#include <stdlib.h>
+
+int main(int argc, char** argv) {
+  char* endptr;
+  --argc, ++argv;
+  double total = 0.0;
+  for (; argc; argc--, argv++) {
+    total += strtod(*argv, &endptr);
+  }
+  printf("total: %g\n", total);
+  return 0;
+}