DIsable reorder_blocks_and_partition for DWARF2 unwinding

[Dehao Chen]

This patch disables reorder_blocks_and_partition for DWARF2 unwinding.
This is causing an internal application to segfault when built with
AutoFDO+EH. Unfortunately, I don't have a small reproducible. But from
the comment above the code, I do not see why UI_DWARF2 will survive
the issue. Any comments?

Bootstrapped and test on-going.

OK for trunk?

Thanks,
Dehao

ChangeLog:

2015-06-23  Dehao Chen  <dehao@google.com>

* opts.c(finish_options): Disable reorder_blocks_and_partition for DWARF2.


Index: opts.c
===================================================================
--- opts.c (revision 220823)
+++ opts.c (working copy)
@@ -740,7 +740,7 @@ finish_options (struct gcc_options *opts, struct g

   if (opts->x_flag_exceptions
       && opts->x_flag_reorder_blocks_and_partition
-      && (ui_except == UI_SJLJ || ui_except >= UI_TARGET))
+      && (ui_except >= UI_SJLJ))
     {
       if (opts_set->x_flag_reorder_blocks_and_partition)
         inform (loc,