[binutils][Arm] Fix Branch Future relocation handling and testisms

[binutils][Arm] Fix Branch Future relocation handling and testisms

bfd/ChangeLog:
2019-05-21  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	PR/target 24460
	* elf32-arm.c (get_value_helper): Remove.
	(elf32_arm_final_link_relocate): Fix branch future relocations.

gas/ChangeLog:
2019-05-21  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	* testsuite/gas/arm/armv8_1-m-bf.d: Allow different branch target naming
	conventions.
	* testsuite/gas/arm/armv8_1-m-bfl.d: Likewise.
	* testsuite/gas/arm/armv8_1-m-bfcsel.d: Likewise.
	* testsuite/gas/arm/armv8_1-m-loloop.d: Likewise.
	* testsuite/gas/arm/armv8_1-m-bf-rel.d: Skip for vxworks.
	* testsuite/gas/arm/armv8_1-m-bf-rela.d: New test.
	* testsuite/gas/arm/armv8_1-m-bfl-rel.d: Skip for vxworks.
	* testsuite/gas/arm/armv8_1-m-bfl-rela.d: New test.

ld/ChangeLog:
2019-05-21  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	* testsuite/ld-arm/arm-elf.exp: Add tests
	* testsuite/ld-arm/bfs-0.s: New test.
	* testsuite/ld-arm/bfs-1.s: New test.
	* testsuite/ld-arm/branch-futures.d: New test.