Add range checks to local array accesses in elf32-arm.c.

Add range checks to local array accesses in elf32-arm.c.

bfd	* elf32-arn.c (struct elf_arm_obj_tdata): Add num_entries field.
	(elf32_arm_num_entries): New macro.
	(elf32_arm_allocate_local_sym_info): Initialise the new field.
	Allocate arrays individually so that buffer overruns can be
	detected by memory checkers.
	(elf32_arm_create_local_iplt): Check num_entries.
	(elf32_arm_get_plt_info): Likewise.
	(elf32_arm_final_link_relocate): Likewise.
	(elf32_arm_check_relocs): Likewise.
	(elf32_arm_size_dynamic_sections): Likewise.
	(elf32_arm_output_arch_local_syms): Likewise.