patch 8.0.1222: test functions interfere with each other

Problem:    Test functions interfere with each other.
Solution:   Cleanup tab pages, windows and buffers.  Reset option.
diff --git a/src/testdir/test_lispwords.vim b/src/testdir/test_lispwords.vim
index c7eda83..4c05504 100644
--- a/src/testdir/test_lispwords.vim
+++ b/src/testdir/test_lispwords.vim
@@ -78,4 +78,5 @@
 
   enew!
   let &cpoptions=save_copt
+  set nolisp
 endfunc