Bug#666106: kfreebsd-i386: Exceptions with tracebacks in task rendezvous cause STORAGE_ERROR

[Nicolas Boulenguez <nicolas@debian.org>]

Package: gnat-5
Followup-For: Bug #666106

With gnat-6/6.1.1-8, the following reproducer should display "No bug."
and causes a segmentation fault instead.  This is most probably a new
symptom for the same issue.

# r.adb:
with Ada.Text_IO; use Ada.Text_IO;
procedure R is
   F : File_Type;
begin
   Open (F, In_File, "empty.txt");
   Skip_Line (F);
exception
   when End_Error =>
      Put_Line ("No bug.");
end R;
# touch empty.txt
# gnatmake r.adb -bargs -E
# ./r