patch 8.1.0105: all tab stops are the same

Problem:    All tab stops are the same.
Solution:   Add the variable tabstop feature. (Christian Brabandt,
            closes #2711)
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index 6a0126b..94e527b 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -147,8 +147,8 @@
 	    test_perl.res \
 	    test_plus_arg_edit.res \
 	    test_preview.res \
-	    test_prompt_buffer.res \
 	    test_profile.res \
+	    test_prompt_buffer.res \
 	    test_python2.res \
 	    test_python3.res \
 	    test_pyx2.res \
@@ -180,6 +180,7 @@
 	    test_undo.res \
 	    test_user_func.res \
 	    test_usercommands.res \
+	    test_vartabs.res \
 	    test_viminfo.res \
 	    test_vimscript.res \
 	    test_visual.res \