patch 8.0.1670: terminal window tests are still a bit flaky

Problem:    Terminal window tests are still a bit flaky.
Solution:   Increase the waiting time for the buffer to be created.

src/testdir/test_terminal.vim

@@ -1061,7 +1061,7 @@ func Api_drop_common(options)
 	\ "set t_ts=",
 	\ ], 'Xscript')
   let buf = RunVimInTerminal('-S Xscript', {})
-  call WaitFor({-> bufnr('Xtextfile') > 0})
+  call WaitFor({-> bufnr('Xtextfile') > 0}, 2000)
   call assert_equal('Xtextfile', expand('%:t'))
   call assert_true(winnr('$') >= 3)
   return buf

src/version.c

@@ -762,6 +762,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1670,
 /**/
     1669,
 /**/