udhcpc: fix a problem with binary-encoded options #2

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

function                                             old     new   delta
attach_option                                        416     413      -3
allocate_tempopt_if_needed                            74       -     -74

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

function                                             old     new   delta
set_mode                                             759     725     -34

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
stty: disable CIBAUD leak check - it is not necessary on Linux

function                                             old     new   delta
stty_main                                           1233    1196     -37

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