[Patch] fix gas crash on missing .seh_endproc

[Nick Clifton]

Hi Tristan,

>      gas/
>          * testsuite/gas/pe/seh-x64-err-2.s: New test.
>          * testsuite/gas/pe/seh-x64-err-2.l: New stderr output.
>          * testsuite/gas/pe/pe.exp: Add test.
>          * config/obj-coff-seh.c (obj_coff_seh_do_final): Don't try to end
>          seh part.

Approved - please apply.

Cheers
  Nick