libbb: ensure mode_string is NUL terminated

If the mode_string array is no longer static we can't rely on
it being NUL terminated.

function                                             old     new   delta
bb_mode_string                                       115     118      +3

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
1 file changed