[ARC] Refactored location where GOT information is collected.

[ARC] Refactored location where GOT information is collected.

Change location where GOT information is collected for ARC target, avoiding
posible use conflicts of the previous .got field in the symbols hash_entry.

bfd/
2018-03-01  Cupertino Miranda  <cmiranda@synopsys.com>

	* arc-got.h (get_got_entry_list_for_symbol): Changed.
	* ef32-arc.c (struct elf_arc_link_hash_entry): Moved and changed.
	(elf_arc_link_hash_newfunc): Changed.
	(arc_elf_link_hash_table_create): Removed old initializations.
	(elf_arc_relocate_section, elf_arc_finish_dynamic_symbol): Changed.