Isolated emscripten in new lib

lib/emscripten/emtests/test_emulate_function_pointer_casts.cpp

@@ -0,0 +1,24 @@
+// Copyright 2017 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 <math.h>
+
+// We have to use a proxy function 'acos_test' here because the updated libc++ library provides a set of overloads to acos,
+// this has the result that we can't take the function pointer to acos anymore due to failed overload resolution.
+// This proxy function has no overloads so it's allowed to take the function pointer directly.
+double acos_test(double x) {
+  return acos(x);
+}
+
+typedef double (*ddd)(double x, double unused);
+typedef int    (*iii)(int x,    int unused);
+
+int main() {
+  volatile ddd d = (ddd)acos_test;
+  volatile iii i = (iii)acos_test;
+  printf("|%.3f,%d|\n", d(0.3, 0.6), i(0, 0));
+  return 0;
+}