patch 8.1.1093: support for outdated tags format slows down tag parsing

Problem:    Support for outdated tags format slows down tag parsing.
Solution:   Remove FEAT_TAG_OLDSTATIC.
diff --git a/src/feature.h b/src/feature.h
index 63b5536..b900569 100644
--- a/src/feature.h
+++ b/src/feature.h
@@ -305,12 +305,9 @@
 #endif
 
 /*
- * +tag_old_static	Old style static tags: "file:tag  file  ..".  Slows
- *			down tag searching a bit.
+ * +tag_old_static	Old style static tags: "file:tag  file  ..".
+ *			Support was removed in 8.1.1093.
  */
-#ifdef FEAT_NORMAL
-# define FEAT_TAG_OLDSTATIC
-#endif
 
 /*
  * +cscope		Unix only: Cscope support.