ppc _bfd_clear_contents

ppc _bfd_clear_contents

ppc32 isn't susceptible to the PR33223 segfault, but could hit a
_bfd_clear_contents segfault with a carefully crafted invalid object.

	* elf32-ppc.c (ARRAY_SIZE): Define.
	(ppc_elf_howto_init): Use ARRAY_SIZE.
	(ppc_elf_reloc_name_lookup): Likewise.
	(ppc_elf_info_to_howto): Likewise, and consolidate error
	handling.
	(ppc_elf_check_relocs): Guard against segfaults caused by a NULL
	howto passed to _bfd_clear_contents.  Use ARRAY_SIZE.