Several fixes related to ARC PIE support.

Several fixes related to ARC PIE support.

Fixed conditions related to dynamic relocs relative offset patching.
Added arc_link_hash_table to be able to always generate and track
.rela.bss section.

bfd/ChangeLog:

Cupertino Miranda  <cmiranda@synopsys.com>

	* elf-bfd.h: Added ARC_ELF_DATA to enum elf_target_id.
	* elf32-arc.c (struct elf_arc_link_hash_entry): Added.
	(struct elf_arc_link_hash_table): Likewise.
	(elf_arc_link_hash_newfunc): Likewise.
	(elf_arc_link_hash_table_free): Likewise.
	(arc_elf_link_hash_table_create): Likewise.
	(elf_arc_relocate_section): Fixed conditions related to dynamic
	(elf_arc_check_relocs): Likewise.
	(arc_elf_create_dynamic_sections): Added
	(elf_arc_adjust_dynamic_symbol): Changed access to .rela.bss to be done
	through the hash table.