patch 8.0.0594: build failure when windows feature is missing

Problem:    Build failure when windows feature is missing.
Solution:   Add #ifdef.

src/screen.c

@@ -275,7 +275,9 @@ redraw_buf_and_status_later(buf_T *buf, int type)
 	if (wp->w_buffer == buf)
 	{
 	    redraw_win_later(wp, type);
+#ifdef FEAT_WINDOWS
 	    wp->w_redr_status = TRUE;
+#endif
 	}
     }
 }

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    594,
 /**/
     593,
 /**/