Configure: the --build= option.

If set, its value is output in "nginx -v" and in the error log.
diff --git a/src/os/unix/ngx_posix_init.c b/src/os/unix/ngx_posix_init.c
index 58e6f76..9a4de02 100644
--- a/src/os/unix/ngx_posix_init.c
+++ b/src/os/unix/ngx_posix_init.c
@@ -82,7 +82,7 @@
 void
 ngx_os_status(ngx_log_t *log)
 {
-    ngx_log_error(NGX_LOG_NOTICE, log, 0, NGINX_VER);
+    ngx_log_error(NGX_LOG_NOTICE, log, 0, NGINX_VER_BUILD);
 
 #ifdef NGX_COMPILER
     ngx_log_error(NGX_LOG_NOTICE, log, 0, "built by " NGX_COMPILER);