vim-patch:8.1.0145: test with grep is failing on MS-Windows

Problem:    Test with grep is failing on MS-Windows.
Solution:   Skip the test.
851332ea9c

src/nvim/testdir/test_quickfix.vim

@@ -3494,6 +3494,8 @@ func Xautocmd_changelist(cchar)
   call assert_equal(4, line('.'))
   autocmd! QuickFixCmdPost
 
+  " The grepprg may not be set on non-Unix systems
+  if has('unix')
     " Test for grep/lgrep
     call g:Xsetlist([], 'f')
     Xexpr 'Xtestfile1:2:Line2'
@@ -3502,6 +3504,7 @@ func Xautocmd_changelist(cchar)
     call assert_equal('Xtestfile2', bufname(''))
     call assert_equal(5, line('.'))
     autocmd! QuickFixCmdPost
+  endif
 
   " Test for vimgrep/lvimgrep
   call g:Xsetlist([], 'f')