Add nacl-clang testing to SCons

pnacl/support/clang_direct/crtbegin.c

 /*
  * Copyright (c) 2014 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /*
  * This is nacl-clang's crtbegin file (crtbegin.o, crtbeginS.o, crtbeginT.o).
  * Currently we only support static linking and it only supports being used
  * as crtbeginT.o (see __dso_handle below).
- * Currently it is also just an aggregation of what PNaCl uses, and is enough
- * to compile our tests, but in particular C++ EH doesn't work yet.
- * TODO(dschuff): Make EH work.
  */
 
 /*
  * HACK:
  * The real structure is defined in unwind-dw2-fde.h
  * this is something that is at least twice as big.
  */
 struct object {
   void *p[16] __attribute__((aligned(8)));
 };
@@ skipping 44 matching lines @@
  * http://gcc.gnu.org/ml/gcc-patches/1999-12n/msg00664.html
  *
  * (Note that __cxa_* functions are usually provided by libsupc++ or
  * its equivalent, but __cxa_atexit() happens to be provided by libc.)
  *
  * __dso_handle is zero for the main executable, which is the only
  * case currently supported by this crtbegin.
  */
 
 void *__dso_handle = 0;