Configure: the --build= option.

If set, its value is output in "nginx -v" and in the error log.
diff --git a/src/core/nginx.c b/src/core/nginx.c
index 4cc8082..c75ee4f 100644
--- a/src/core/nginx.c
+++ b/src/core/nginx.c
@@ -217,7 +217,7 @@
     }
 
     if (ngx_show_version) {
-        ngx_write_stderr("nginx version: " NGINX_VER NGX_LINEFEED);
+        ngx_write_stderr("nginx version: " NGINX_VER_BUILD NGX_LINEFEED);
 
         if (ngx_show_help) {
             ngx_write_stderr(
diff --git a/src/core/nginx.h b/src/core/nginx.h
index 8c7800a..12e6e8a 100644
--- a/src/core/nginx.h
+++ b/src/core/nginx.h
@@ -13,6 +13,12 @@
 #define NGINX_VERSION      "1.7.1"
 #define NGINX_VER          "nginx/" NGINX_VERSION
 
+#ifdef NGX_BUILD
+#define NGINX_VER_BUILD    NGINX_VER " (" NGX_BUILD ")"
+#else
+#define NGINX_VER_BUILD    NGINX_VER
+#endif
+
 #define NGINX_VAR          "NGINX"
 #define NGX_OLDPID_EXT     ".oldbin"
 
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);
diff --git a/src/os/win32/ngx_win32_init.c b/src/os/win32/ngx_win32_init.c
index f7153fc..6fa1a57 100644
--- a/src/os/win32/ngx_win32_init.c
+++ b/src/os/win32/ngx_win32_init.c
@@ -247,7 +247,7 @@
 {
     ngx_osviex_stub_t  *osviex_stub;
 
-    ngx_log_error(NGX_LOG_NOTICE, log, 0, NGINX_VER);
+    ngx_log_error(NGX_LOG_NOTICE, log, 0, NGINX_VER_BUILD);
 
     if (osviex) {