Allow veneers to claim veneered symbols

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

bfd/
	* elf32-arm.c (enum elf32_arm_stub_type): New max_stub_type
	enumerator.
	(arm_stub_sym_claimed): New function.
	(elf32_arm_create_stub): Use veneered symbol name and section if
	veneer needs to claim its symbol, and keep logic unchanged otherwise.
	(arm_stub_claim_sym): New function.
	(arm_map_one_stub): Call arm_stub_claim_sym if veneer needs to claim
	veneered symbol, otherwise create local symbol as before.