patch 9.0.0180: stray logfile appears when running tests

Problem:    Stray logfile appears when running tests.
Solution:   Remove ch_logfile() calls.

src/testdir/test_textprop.vim

@@ -974,12 +974,10 @@ func Test_prop_line2byte()
   call assert_equal(1489, line2byte(400))
   bwipe!
 
-call ch_logfile('logfile', 'w')
   " Add many lines so that the data block is split.
   " With and without props should give the same result.
   call Run_test_with_line2byte(0)
   call Run_test_with_line2byte(1)
-call ch_logfile('', 'w')
 
   call prop_type_delete('comment')
 endfunc

src/version.c

@@ -735,6 +735,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    180,
 /**/
     179,
 /**/