ELF output symbol hooks int vs. bfd_boolean

ELF output symbol hooks int vs. bfd_boolean

elf_backend_link_output_symbol_hook and elf_link_output_symstrtab may
return 2 when a symbol is to be discarded.  Update places that use
bfd_boolean rather than int for these functions.

	* elflink.c (elf_link_output_symstrtab): Make flinfo parameter
	a void pointer.
	(bfd_elf_final_link): Delete out_sym_func typedef and don't cast
	elf_link_output_symstrtab when calling output_arch_syms and
	output_arch_local_syms.
	* elf-bfd.h (struct elf_backend_data <elf_backend_output_arch_syms,
	elf_backend_output_arch_local_syms>): Change return type of func
	arg to match elf_link_output_symstrtab.
	* elf-vxworks.h (elf_vxworks_link_output_symbol_hook): Correct
	return type.
	* elf32-nds32.c (nds32_elf_output_symbol_hook): Correct return type.
	(nds32_elf_output_arch_syms): Correct func return type.