patch 9.0.1118: sporadic test failures when using a terminal window

Problem:    Sporadic test failures when using a terminal window.
Solution:   Adjust waiting times. (James McCoy, closes #11763)

src/testdir/term_util.vim

@@ -141,6 +141,9 @@ func StopVimInTerminal(buf, kill = 1)
 
   call assert_equal("running", term_getstatus(a:buf))
 
+  " Wait for all the pending updates to terminal to complete
+  call TermWait(a:buf)
+
   " CTRL-O : works both in Normal mode and Insert mode to start a command line.
   " In Command-line it's inserted, the CTRL-U removes it again.
   call term_sendkeys(a:buf, "\<C-O>:\<C-U>qa!\<cr>")