patch 8.1.1651: suspend test is flaky on some systems

Problem:    Suspend test is flaky on some systems.
Solution:   Wait for the shell prompt to show. (Yee Cheng Chin, closes #4632)

Author: brammool

src/testdir/test_suspend.vim

@@ -54,6 +54,8 @@ func Test_suspend()
   " Quit gracefully to dump coverage information.
   call term_sendkeys(buf, ":qall!\<CR>")
   call term_wait(buf)
+  " Wait until Vim actually exited and shell shows a prompt
+  call WaitForAssert({-> assert_match('[$#] $', term_getline(buf, '.'))})
   call StopShellInTerminal(buf)
 
   exe buf . 'bwipe!'

src/version.c

@@ -777,6 +777,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1651,
 /**/
     1650,
 /**/