Refactor Cortex-A8 erratum workaround in preparation

Refactor Cortex-A8 erratum workaround in preparation

2016-05-10  Thomas Preud'homme  <thomas.preudhomme@arm.com>

bfd/
	* elf32-arm.c (enum elf32_arm_stub_type): Delete
	arm_stub_a8_veneer_lwm enumerator.
	(arm_stub_a8_veneer_lwm): New unsigned constant to replace
	aforementioned enumerator.
	(struct elf32_arm_stub_hash_entry): Delete target_addend
	field and add source_value.
	(struct a8_erratum_fix): Delete addend field and add target_offset.
	(stub_hash_newfunc): Initialize source_value field amd remove
	initialization for target_addend.
	(arm_build_one_stub): Stop special casing Thumb relocations: promote
	the else to being always executed, moving the
	arm_stub_a8_veneer_b_cond specific code in it.  Remove
	stub_entry->target_addend from points_to computation.
	(cortex_a8_erratum_scan): Store in a8_erratum_fix structure the offset
	to target symbol from start of section rather than the offset from the
	stub address.
	(elf32_arm_size_stubs): Set stub_entry's source_value and target_value
	fields from struct a8_erratum_fix's offset and target_offset
	respectively.
	(make_branch_to_a8_stub): Rename target variable to loc.  Compute
	veneered_insn_loc and loc using stub_entry's source_value.