Allow stubs without associated input section in ARM backend

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

bfd/
	* bfd-in.h (elf32_arm_size_stubs): Add an output section parameter.
	* bfd-in2.h: Regenerated.
	* elf32-arm.c (struct elf32_arm_link_hash_table): Add an output section
	parameter to add_stub_section callback.
	(elf32_arm_create_or_find_stub_sec): Get output section from link_sec
	and pass it down to add_stub_section.
	(elf32_arm_add_stub): Set section to stub_sec if NULL before using it
	for error message.
	(elf32_arm_size_stubs): Add output section parameter to
	add_stub_section function pointer parameter.

ld/
	* emultempl/armelf.em (elf32_arm_add_stub_section): Add output_section
	parameter and rename input_section parameter to after_input_section.
	Append input stub section to the output section if after_input_section
	is NULL.