Events: fixed setting of IP_BIND_ADDRESS_NO_PORT/SO_REUSEADDR.

The IP_BIND_ADDRESS_NO_PORT option is set on upstream sockets
if proxy_bind does not specify a port.  The SO_REUSEADDR option
is set on UDP upstream sockets if proxy_bind specifies a port.

Due to checking of the wrong port, IP_BIND_ADDRESS_NO_PORT was
never set, and SO_REUSEPORT was always set.

src/event/ngx_event_connect.c

diff --git a/src/event/ngx_event_connect.c b/src/event/ngx_event_connect.c
index 30cb59a..06534ef 100644
--- a/src/event/ngx_event_connect.c
+++ b/src/event/ngx_event_connect.c
@@ -91,7 +91,7 @@
 #endif
 
 #if (NGX_HAVE_IP_BIND_ADDRESS_NO_PORT || NGX_LINUX)
-        port = ngx_inet_get_port(pc->sockaddr);
+        port = ngx_inet_get_port(pc->local->sockaddr);
 #endif
 
 #if (NGX_HAVE_IP_BIND_ADDRESS_NO_PORT)