Fix: nm: SEGV on unknow address at nm.c:718 in print_symname

Fix: nm: SEGV on unknow address at nm.c:718 in print_symname

  PR 30886 * elf-bfd.h (struct elf_obj_tdata): Add dt_strsz field.
  * elf.c (_bfd_elf_get_dynamic_symbols): Add a NUL byte at the end of the string table. Initialise the dt_strsz field. (_bfd_elf_slurp_version_tables): Only free the contents if they were malloc'ed. Add checks before setting string pointers in the dt_strtab buffer.