libbb: Add xsetegid(), xseteuid(), xopen_as_uid_gid() functions

Signed-off-by: Ryan Mallon <rmallon@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
wall,crontab: use xopen_as_uid_gid()

This fixes a narrow security race in crontab.

function                                             old     new   delta
xopen_as_uid_gid                                       -      80     +80
seteuid                                                -      64     +64
setegid                                                -      64     +64
setreuid                                               -      37     +37
xseteuid                                               -      22     +22
xsetegid                                               -      22     +22
crontab_main                                         590     577     -13
setfsuid                                              33       -     -33
setfsgid                                              33       -     -33
wall_main                                            138     102     -36
open_as_user                                         109       -    -109

   text    data     bss     dec     hex filename
 893539     497    7568  901604   dc1e4 busybox_old
 893618     497    7568  901683   dc233 busybox_unstripped

Signed-off-by: Ryan Mallon <rmallon@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
awk: fix length(array)

function                                             old     new   delta
evaluate                                            3526    3548     +22

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
init: better --help text

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
wget: add support for connect timeout

function                                             old     new   delta
open_socket                                           33      64     +31
wget_main                                           2182    2194     +12

Signed-off-by: Lauri Kasanen <curaga@operamail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>