libbb: add setsockopt_foo helpers

libbb: add setsockopt_foo helpers

function                                             old     new   delta
setsockopt_int                                         -      23     +23
do_load                                              918     934     +16
setsockopt_SOL_SOCKET_int                              -      14     +14
setsockopt_keepalive                                   -      10     +10
setsockopt_SOL_SOCKET_1                                -      10     +10
buffer_fill_and_print                                169     178      +9
setsockopt_1                                           -       8      +8
nfsmount                                            3560    3566      +6
redirect                                            1277    1282      +5
tcpudpsvd_main                                      1782    1786      +4
d6_send_kernel_packet                                272     275      +3
i2cget_main                                          380     382      +2
ed_main                                             2544    2545      +1
scan_recursive                                       380     378      -2
nbdclient_main                                       492     490      -2
hash_find                                            235     233      -2
cmdputs                                              334     332      -2
parse_command                                       1443    1440      -3
static.two                                             4       -      -4
ntpd_main                                           1039    1035      -4
const_int_1                                            4       -      -4
const_IPTOS_LOWDELAY                                   4       -      -4
RCVBUF                                                 4       -      -4
ntp_init                                             474     469      -5
change_listen_mode                                   316     310      -6
uevent_main                                          416     409      -7
arping_main                                         1697    1690      -7
telnet_main                                         1612    1603      -9
socket_want_pktinfo                                   42      33      -9
setsockopt_reuseaddr                                  21      10     -11
setsockopt_broadcast                                  21      10     -11
httpd_main                                           772     757     -15
get_remote_transfer_fd                               109      94     -15
make_new_session                                     503     487     -16
ftpd_main                                           2177    2160     -17
read_bunzip                                         1896    1866     -30
common_traceroute_main                              4099    4058     -41
common_ping_main                                    1836    1783     -53
------------------------------------------------------------------------------
(add/remove: 5/4 grow/shrink: 8/21 up/down: 111/-283)        Total: -172 bytes

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