Apply revision 1.56 from binutils CVS:

Catch NULL bfd pointers passed to bfd_archive_filename.

Fixes a core dump in ld(8) when loading certain LKMs.

Approved by mrg.

gnu/dist/binutils/bfd/bfd.c

@@ -526,6 +526,9 @@ const char *
 bfd_archive_filename (abfd)
      bfd *abfd;
 {
+  if (abfd == NULL)
+    return _("<unknown>");
+
   if (abfd->my_archive)
     {
       static size_t curr = 0;