Fix immediate Darwin crash

[Josh Matthews <josh at joshmatthews dot net>]

Attempting to debug any binary on Darwin currently triggers an
immediate segfault. This patch corrects that.

Cheers,
Josh

2012-10-21  Josh Matthews  <josh@joshmatthews.net>

        * mach-o.c (bfd_mach_o_close_and_cleanup): Clear tdata
        pointer to avoid incorrect archive data deletion.
        * archive.c (_bfd_archive_close_and_cleanup): Avoid
        accessing archive cache data when tdata is null.

diff --git a/bfd/archive.c b/bfd/archive.c
index 8e8fd2d..3771272 100644
--- a/bfd/archive.c
+++ b/bfd/archive.c
@@ -2715,7 +2715,8 @@ _bfd_archive_close_and_cleanup (bfd *abfd)
     {
       bfd *nbfd;
       bfd *next;
-      htab_t htab;
+      struct artdata *ardata;
+      htab_t htab = NULL;

       /* Close nested archives (if this bfd is a thin archive).  */
       for (nbfd = abfd->nested_archives; nbfd; nbfd = next)
@@ -2724,7 +2725,11 @@ _bfd_archive_close_and_cleanup (bfd *abfd)
          bfd_close (nbfd);
        }

-      htab = bfd_ardata (abfd)->cache;
+      ardata = bfd_ardata (abfd);
+      if (ardata)
+        {
+          htab = ardata->cache;
+        }
       if (htab)
        {
          htab_traverse_noresize (htab, archive_close_worker, NULL);
diff --git a/bfd/mach-o.c b/bfd/mach-o.c
index 0379f4f..7c44c5a 100644
--- a/bfd/mach-o.c
+++ b/bfd/mach-o.c
@@ -4863,6 +4863,10 @@ bfd_mach_o_close_and_cleanup (bfd *abfd)
           free (dsym_filename);
         }
     }
+  else if (bfd_get_format (abfd) == bfd_archive)
+    {
+      abfd->tdata.mach_o_fat_data = NULL;
+    }

   return _bfd_generic_close_and_cleanup (abfd);
 }