patch 9.1.0150: Several minor 'winfixbuf' issues

Problem:  several minor 'winfixbuf' issues exist, mostly relating to the
          quickfix list
Solution: address them and adjust tests. Retab and reflow a few things too.
          (Sean Dewar)

Things touched include:

- Replace the semsgs with gettext'd emsgs.

- Handle window switching in ex_listdo properly, so curbuf and curwin
  are kept in-sync and trigger autocommands; handle those properly.

- Don't change the list entry index in qf_jump_edit_buffer if we fail
  due to 'wfb' (achieved by returning FAIL; QF_ABORT should only be used
  if the list was changed).

- Make qf_jump_edit_buffer actually switch to prevwin when using `:cXX`
  commands **outside** of the list window if 'wfb' is set in curwin.
  Handle autocommands properly in case they mess with the list.

  NOTE: previously, it seemed to split if 'wfb' was set, but do nothing
  and fail if prevwin is *valid*. This behaviour seemed strange, and maybe
  unintentional? Now it aligns more with what's described for the `:cXX`
  commands in the original PR description when used outside a list window,
  I think.

- In both functions, only consider prevwin if 'wfb' isn't set for it;
  fallback to splitting otherwise.

- Use win_split to split. Not sure if there was a specific reason for
  using ex_splitview. win_split is simpler and respects modifiers like
  :vertical that may have been used. Plus, its return value can be checked
  for setting opened_window in qf code (technically win_split_ins autocmds
  could immediately close it or change windows, in which the qf code might
  close some other window on failure; it's already the case elsewhere,
  though).

closes: #14142

Signed-off-by: Sean Dewar <6256228+seandewar@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/ex_cmds2.c

@@ -460,26 +460,33 @@ ex_listdo(exarg_T *eap)
 
     if (curwin->w_p_wfb)
     {
-        if ((eap->cmdidx == CMD_ldo || eap->cmdidx == CMD_lfdo) && !eap->forceit)
-        {
-            // Disallow :ldo if 'winfixbuf' is applied
-            semsg("%s", e_winfixbuf_cannot_go_to_buffer);
-            return;
-        }
+	if ((eap->cmdidx == CMD_ldo || eap->cmdidx == CMD_lfdo) &&
+		!eap->forceit)
+	{
+	    // Disallow :ldo if 'winfixbuf' is applied
+	    emsg(_(e_winfixbuf_cannot_go_to_buffer));
+	    return;
+	}
 
-        if (win_valid(prevwin))
-            // Change the current window to another because 'winfixbuf' is enabled
-            curwin = prevwin;
-        else
-        {
-            // Split the window, which will be 'nowinfixbuf', and set curwin to that
-            exarg_T new_eap;
-            CLEAR_FIELD(new_eap);
-            new_eap.cmdidx = CMD_split;
-            new_eap.cmd = (char_u *)"split";
-            new_eap.arg = (char_u *)"";
-            ex_splitview(&new_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 (curwin->w_p_wfb)
+	    {
+		// Autocommands set 'winfixbuf' or sent us to another window
+		// with it set.  Give up.
+		emsg(_(e_winfixbuf_cannot_go_to_buffer));
+		return;
+	    }
+	}
     }
 
 #if defined(FEAT_SYN_HL)