S/390: Disable relocation sort against code sections.

S/390: Disable relocation sort against code sections.

When downgrading from GD to IE model we rewrite the call to
__tls_get_offset to a 64 bit load instruction. This relies on the fact
that the additional relocation for the call target has already been
executed when doing the rewrite.

   f1018:       e3 20 d0 00 00 04       lg      %r2,0(%r13)
   f101e:       c0 e5 00 00 00 00       brasl   %r14,f101e <__res_init+0x1e>
                        f101e: R_390_TLS_GDCALL __libc_resp
                        f1020: R_390_PLT32DBL   __tls_get_offset+0x2

0000000f1020  39f6c00000014 R_390_PLT32DBL    0000000000000000 __tls_get_offset + 2
0000000f101e  3afb700000026 R_390_TLS_GDCALL  0000000000000008 __libc_resp + 0

Due to the reloc sorting the order changed an the PLT32DBL reloc is
executed after the rewrite and overwrites part of the load instruction
with garbage.

bfd/
2015-03-14  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* elf-s390-common.c (elf_s390_elf_sort_relocs_p): Don't sort
	relocs against code sections.
	* elf32-s390.c: Define elf_backend_sort_relocs_p.
	* elf64-s390.c: Likewise.