patch 9.1.0152: Coverity complains about ignoring return value

Problem:  Coverity complains about ignoring return value of win_split()
          (after v9.1.150)
Solution: Check if win_split() failed, add winfixbuf.res to Makefile

src/ex_cmds2.c

@@ -469,15 +469,14 @@ ex_listdo(exarg_T *eap)
 	}
 
 	if (win_valid(prevwin) && !prevwin->w_p_wfb)
-	{
 	    // 'winfixbuf' is set; attempt to change to a window without it.
 	    win_goto(prevwin);
-	}
 	if (curwin->w_p_wfb)
 	{
 	    // Split the window, which will be 'nowinfixbuf', and set curwin to
 	    // that
-	    win_split(0, 0);
+	    if (win_split(0, 0) == FAIL)
+		return; // error message already given
 
 	    if (curwin->w_p_wfb)
 	    {

src/testdir/Make_all.mak

@@ -558,6 +558,7 @@ NEW_TESTS_RES = \
 	test_window_cmd.res \
 	test_window_id.res \
 	test_windows_home.res \
+	test_winfixbuf.res \
 	test_wordcount.res \
 	test_writefile.res \
 	test_xxd.res \

src/testdir/test_winfixbuf.vim

@@ -3248,4 +3248,15 @@ func Test_quickfix_changed_split_failed()
   augroup! QfChanged
 endfunc
 
+func Test_bufdo_splitwin_fails()
+  call s:reset_all_buffers()
+  let other = s:make_buffer_pairs()
+  " Make sure there is not enough room to
+  " split the winfixedbuf window
+  let &winheight=&lines
+  let &winminheight=&lines-2
+  call assert_fails(':bufdo echo 1', 'E36:')
+  set winminheight&vim winheight&vim
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    152,
 /**/
     151,
 /**/