*: move get_sock_lsa and xwrite_str to libbb, use where appropriate

function                                             old     new   delta
get_sock_lsa                                           -      72     +72
buffer_fill_and_print                                179     196     +17
parse_expr                                           824     832      +8
read_base64                                          343     348      +5
nameval                                              202     206      +4
fbset_main                                          1694    1698      +4
expand                                              1849    1853      +4
udhcp_send_kernel_packet                             249     252      +3
udhcp_get_option                                     223     222      -1
chat_main                                           1246    1245      -1
pack_gzip                                           1661    1659      -2
doset                                                299     297      -2
bb__parsespent                                       119     117      -2
test_main                                            260     257      -3
qgravechar                                           109     106      -3
tcpudpsvd_main                                      1834    1830      -4
sysctl_display_all                                   589     580      -9
xopen_xwrite_close                                    44      33     -11
prs                                                   30      18     -12
find_main                                            418     406     -12
full_write2_str                                       25      12     -13
adduser_main                                         667     654     -13
evaltreenr                                           817     802     -15
evaltree                                             817     802     -15
tftpd_main                                           526     493     -33
ftpd_main                                           2050    1990     -60
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 7/18 up/down: 117/-211)         Total: -94 bytes

diff --git a/libbb/xconnect.c b/libbb/xconnect.c
index 2eb4cb9..9758445 100644
--- a/libbb/xconnect.c
+++ b/libbb/xconnect.c
@@ -35,6 +35,19 @@
 	return r;
 }
 
+len_and_sockaddr* FAST_FUNC get_sock_lsa(int fd)
+{
+	len_and_sockaddr *lsa;
+	socklen_t len = 0;
+
+	/* Can be optimized to do only one getsockname() */
+	if (getsockname(fd, NULL, &len) != 0)
+		return NULL;
+	lsa = xzalloc(LSA_LEN_SIZE + len);
+	lsa->len = len;
+	getsockname(fd, &lsa->u.sa, &lsa->len);
+	return lsa;
+}
 
 void FAST_FUNC xconnect(int s, const struct sockaddr *s_addr, socklen_t addrlen)
 {
@@ -51,8 +64,9 @@
 
 /* Return port number for a service.
  * If "port" is a number use it as the port.
- * If "port" is a name it is looked up in /etc/services, if it isnt found return
- * default_port */
+ * If "port" is a name it is looked up in /etc/services,
+ * if it isnt found return default_port
+ */
 unsigned FAST_FUNC bb_lookup_port(const char *port, const char *protocol, unsigned default_port)
 {
 	unsigned port_nr = default_port;