PR 1147

PR 1147
* elf32-arm.c (struct _arm_elf_section_data): Turn into a typedef and make the
  mapcount field unsigned.
(struct section_list): New: Used to keep track of which sections have an
  _arm_elf_section_data structure.
(record_section_with_arm_elf_section_data): New function.
(get_arm_elf_section_data): New function.
(unrecord_section_with_arm_elf_section_data): New function.
(elf32_arm_output_symbol_hook): Use get_arm_elf_section_data.
(elf32_arm_new_section_hook): Call record_section_with_arm_elf_section_data.
(elf32_arm_write_section): Use get_arm_elf_section_data and
  unrecord_section_with_arm_elf_section_data.