udhcp: move options.c to common.c; disable unused bool and s16 option code

udhcp: move options.c to common.c; disable unused bool and s16 option code

function                                             old     new   delta
udhcp_add_binary_option                                -      94     +94
udhcp_str2nip                                          -      42     +42
len_of_option_as_string                               12      10      -2
dhcp_option_lengths                                   12      10      -2
udhcpc_main                                         2859    2851      -8
read_nip                                              42       -     -42
xmalloc_optname_optval                               590     536     -54
udhcp_str2optset                                     443     366     -77
udhcp_add_option_string                               86       -     -86
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 0/5 up/down: 136/-271)         Total: -135 bytes

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