ls: -k no longer affects -l's file sizes

ls: -k no longer affects -l's file sizes

This fixes an incompatibility with POSIX 2008 and with BSD.
Problem reported by Abdallah Clark (Bug#9939)
via Alan Curry (Bug#10016).
* NEWS: Document this.
* doc/coreutils.texi (General output formatting): Document the
new -k behavior, and --kibibytes.
* src/ls.c (file_human_output_opts): New static var.
(long_options, usage): Add --kibibytes.
(decode_switches, gobble_file, print_long_format):
Implement the new -k behavior.
* tests/ls/block-size: New file.
* tests/Makefile.am (TESTS): Add it.