ls: get rid of opt_flags[], handle -l1c through option_mask32

ls: get rid of opt_flags[], handle -l1c through option_mask32

function                                             old     new   delta
display_single                                       885     888      +3
scan_and_display_dirs_recur                          496     486     -10
opt_flags                                             11       -     -11
ls_main                                              618     553     -65
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 1/2 up/down: 3/-86)             Total: -83 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>