patch 8.0.0417: test for the clipboard fails sometimes

Problem:    Test for the clipboard fails sometimes.
Solution:   Add it to the flaky tests.

Author: brammool

src/testdir/runtest.vim

@@ -168,6 +168,7 @@ let s:flaky = [
       \ 'Test_oneshot()',
       \ 'Test_pipe_through_sort_all()',
       \ 'Test_pipe_through_sort_some()',
+      \ 'Test_quoteplus()',
       \ 'Test_reltime()',
       \ ]
 

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    417,
 /**/
     416,
 /**/