Upstream: least_conn balancer module.

auto/options

diff --git a/auto/options b/auto/options
index 393be40..11f23c6 100644
--- a/auto/options
+++ b/auto/options
@@ -96,6 +96,7 @@
 HTTP_MP4=NO
 HTTP_GZIP_STATIC=NO
 HTTP_UPSTREAM_IP_HASH=YES
+HTTP_UPSTREAM_LEAST_CONN=YES
 HTTP_UPSTREAM_KEEPALIVE=YES
 
 # STUB
@@ -243,6 +244,8 @@
         --without-http_empty_gif_module) HTTP_EMPTY_GIF=NO          ;;
         --without-http_browser_module)   HTTP_BROWSER=NO            ;;
         --without-http_upstream_ip_hash_module) HTTP_UPSTREAM_IP_HASH=NO ;;
+        --without-http_upstream_least_conn_module)
+                                         HTTP_UPSTREAM_LEAST_CONN=NO ;;
         --without-http_upstream_keepalive_module) HTTP_UPSTREAM_KEEPALIVE=NO ;;
 
         --with-http_perl_module)         HTTP_PERL=YES              ;;