Macro cleanup: PROTO

Regarding dict_lookup() in eval.c: both definitions are the same, the
only difference being the spacing between the indirection operator and
the indentation level.

src/nvim/memline.c

@@ -3000,7 +3000,7 @@ static void ml_lineadd(buf_T *buf, int count)
   }
 }
 
-#if defined(HAVE_READLINK) || defined(PROTO)
+#if defined(HAVE_READLINK)
 /*
  * Resolve a symlink in the last component of a file name.
  * Note that f_resolve() does it for every part of the path, we don't do that