patch 8.1.0811: too many #ifdefs

Problem:    Too many #ifdefs.
Solution:   Graduate FEAT_MBYTE, the final chapter.
diff --git a/src/testdir/test_termencoding.vim b/src/testdir/test_termencoding.vim
index 6192dcf..f4f5c5a 100644
--- a/src/testdir/test_termencoding.vim
+++ b/src/testdir/test_termencoding.vim
@@ -2,7 +2,7 @@
 " setting 'termencoding' to make it work.
 
 " This only works with "iconv".
-if !has('multi_byte') || !has('iconv')
+if !has('iconv')
   finish
 endif