~vcs-imports/busybox/trunk

libbb: use full_write1_str() to shrink busybox_main()

There are two calls to dup2() in busybox_main().  These were
introduced to coerce full_write2_str() into writing to stdout.

The relevant commits were: 21278dff7 (busybox: do not print help
to fd 2, print it to fd 1) and 5a7c72015 (busybox --list option.
+140 bytes. Rob wanted it.)

Later, in commit 729ecb87b (bbconfig: make it independent from
printf functions), the function full_write1_str() was added.

Using this in busybox_main() allows us to drop the dup2() calls.

function                                             old     new   delta
run_applet_and_exit                                  796     760     -36
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-36)             Total: -36 bytes

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