patch 8.1.2096: too many #ifdefs

Problem:    Too many #ifdefs.
Solution:   Graduate FEAT_COMMENTS.
diff --git a/src/feature.h b/src/feature.h
index dc5accc..b2ba162 100644
--- a/src/feature.h
+++ b/src/feature.h
@@ -108,6 +108,7 @@
  * +cmdline_compl	completion of mappings/abbreviations in cmdline mode.
  * +insert_expand	CTRL-N/CTRL-P/CTRL-X in insert mode.
  * +modify_fname	modifiers for file name.  E.g., "%:p:h".
+ * +comments		'comments' option.
  *
  * Obsolete:
  * +tag_old_static	Old style static tags: "file:tag  file  ..".
@@ -496,13 +497,6 @@
 #endif
 
 /*
- * +comments		'comments' option.
- */
-#ifdef FEAT_NORMAL
-# define FEAT_COMMENTS
-#endif
-
-/*
  * +cryptv		Encryption (by Mohsin Ahmed <mosh@sasi.com>).
  */
 #if defined(FEAT_NORMAL) && !defined(FEAT_CRYPT) || defined(PROTO)