eh: ICE with std::initializer_list and ASan [PR115865]

eh: ICE with std::initializer_list and ASan [PR115865]

Here we ICE with -fsanitize=address on

  std::initializer_list x = { 1, 2, 3 };

since r14-8681, which removed .ASAN_MARK calls on TREE_STATIC variables.
That means that lower_try_finally now instead of

  try
    {
      .ASAN_MARK (UNPOISON, &C.0, 12);
      x = {};
      x._M_len = 3;
      x._M_array = &C.0;
    }
  finally
    {
      .ASAN_MARK (POISON, &C.0, 12);
    }

gets:

  try
    {
      x = {};
      x._M_len = 3;
      x._M_array = &C.0;
    }
  finally
    {

    }

and we ICE on the empty finally in lower_try_finally_onedest while
getting get_eh_else.

	PR c++/115865

gcc/ChangeLog:

	* tree-eh.cc (get_eh_else): Check that the result of
	gimple_seq_first_stmt is non-null.

gcc/testsuite/ChangeLog:

	* g++.dg/asan/initlist2.C: New test.

Co-authored-by: Jakub Jelinek  <jakub@redhat.com>