[binutils-gdb] S/390: Fix testsuite segfault added with recent pgste patch.

[sergiodj+buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT 93ec5e23766a9f75aa4950748cf73964028a8d1b ***

Author: Andreas Krebbel <krebbel@linux.vnet.ibm.com>
Branch: master
Commit: 93ec5e23766a9f75aa4950748cf73964028a8d1b

S/390: Fix testsuite segfault added with recent pgste patch.

The recent pgste patch caused several testcases to fail with a
segfault.  Fixed with this patch by adding NULL pointer checks.

regression-tested on s390x.

bfd/ChangeLog:

2017-06-26  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* elf64-s390.c (elf_s390_additional_program_headers): Add NULL
	pointer checks.
	(elf_s390_modify_segment_map): Likewise.
	(bfd_elf_s390_set_options): Lisewise.