Add support for Thumb-2 long branch veneers

Add support for Thumb-2 long branch veneers

2016-06-17  Thomas Preud'homme  <thomas.preudhomme@arm.com>
	    Tony Wang  <tony.wang@arm.com>

bfd/
	* elf32-arm.c (elf32_arm_stub_long_branch_thumb2_only): Define stub
	sequence.
	(stub_long_branch_thumb2_only): Define stub.
	(arm_stub_is_thumb): Add case for arm_stub_long_branch_thumb2_only.
	(arm_stub_long_branch_thumb2_only): Likewise.
	(arm_type_of_stub): Use arm_stub_long_branch_thumb2_only for Thumb-2
	capable targets.

ld/
	* testsuite/ld-arm/arm-elf.exp (Thumb-Thumb farcall M profile):
	Assemble for ARMv6-M.
	(Thumb2-Thumb2 farcall M profile): New testcase.
	* testsuite/ld-arm/farcall-thumb2-thumb2-m.d: New file.
	* testsuite/ld-arm/jump-reloc-veneers-cond-long-backward.d: Update to
	reflect the use of Thumb-2 veneers for Thumb-2 capable targets.
	* testsuite/ld-arm/jump-reloc-veneers-cond-long.d: Likewise.