x86: Add _bfd_x86_elf_link_setup_gnu_properties

x86: Add _bfd_x86_elf_link_setup_gnu_properties

Extract the common parts of elf_i386_link_setup_gnu_properties and
elf_x86_64_link_setup_gnu_properties into a new function.

For x86-64, since PIC PLT layouts are the same as non-PIC PLT layouts,
initialize pic_plt0_entry and pic_plt_entry fields in PLT layouts with
the non-PIC PLT entries.

	* elf32-i386.c (elf_i386_link_setup_gnu_properties): Updated.
	Call _bfd_x86_elf_link_setup_gnu_properties.
	* elf64-x86-64.c (elf_x86_lazy_plt_layout): Initialize
	pic_plt0_entry and pic_plt_entry fields with the non-PIC PLT
	entries.
	(elf_x86_64_non_lazy_plt): Likewise.
	(elf_x86_64_lazy_bnd_plt): Likewise.
	(elf_x86_64_non_lazy_bnd_plt): Likewise.
	(elf_x86_64_lazy_ibt_plt): Likewise.
	(elf_x32_lazy_ibt_plt): Likewise.
	(elf_x86_64_non_lazy_ibt_plt): Likewise.
	(elf_x32_non_lazy_ibt_plt): Likewise.
	(elf_x86_64_nacl_plt): Likewise.
	(elf_x86_64_link_setup_gnu_properties): Updated.  Call
	_bfd_x86_elf_link_setup_gnu_properties.
	* elfxx-x86.c: Include elf-vxworks.h".
	(_bfd_x86_elf_link_setup_gnu_properties): New function.
	* elfxx-x86.h (elf_x86_lazy_plt_layout): Remove "for i386 only"
	comments for pic_plt0_entry and pic_plt_entry.
	(elf_x86_non_lazy_plt_layout): Likewise.
	(elf_x86_plt_layout_table): New.
	(_bfd_x86_elf_link_setup_gnu_properties): Likewise.