patch 9.1.0169: current window number returned by tabpagewinnr may be outdated

Problem:  current window number returned by tabpagewinnr may be outdated
          when called from win_execute for the original tabpage.
Solution: update the original tabpage's tp_curwin in switch_win; use
          {un}use_tabpage instead. Don't do it in restore_win to ensure
          tp_curwin of the temporarily visited tabpage is unchanged from
          switch_win visiting it, as before. (Sean Dewar)

Maybe restore_win should only restore tp_curwin if
`curtab == switchwin->sw_curtab`, in case the user changed tabpages from within
win_execute, but not doing that is consistent with the old behaviour.

related: #14186

Signed-off-by: Sean Dewar <6256228+seandewar@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/evalwindow.c b/src/evalwindow.c
index f9b1c12..cb813a6 100644
--- a/src/evalwindow.c
+++ b/src/evalwindow.c
@@ -1351,13 +1351,8 @@
 	switchwin->sw_curtab = curtab;
 	if (no_display)
 	{
-	    curtab->tp_firstwin = firstwin;
-	    curtab->tp_lastwin = lastwin;
-	    curtab->tp_topframe = topframe;
-	    curtab = tp;
-	    firstwin = curtab->tp_firstwin;
-	    lastwin = curtab->tp_lastwin;
-	    topframe = curtab->tp_topframe;
+	    unuse_tabpage(curtab);
+	    use_tabpage(tp);
 	}
 	else
 	    goto_tabpage_tp(tp, FALSE, FALSE);
@@ -1395,13 +1390,12 @@
     {
 	if (no_display)
 	{
-	    curtab->tp_firstwin = firstwin;
-	    curtab->tp_lastwin = lastwin;
-	    curtab->tp_topframe = topframe;
-	    curtab = switchwin->sw_curtab;
-	    firstwin = curtab->tp_firstwin;
-	    lastwin = curtab->tp_lastwin;
-	    topframe = curtab->tp_topframe;
+	    win_T	*old_tp_curwin = curtab->tp_curwin;
+
+	    unuse_tabpage(curtab);
+	    // Don't change the curwin of the tabpage we temporarily visited.
+	    curtab->tp_curwin = old_tp_curwin;
+	    use_tabpage(switchwin->sw_curtab);
 	}
 	else
 	    goto_tabpage_tp(switchwin->sw_curtab, FALSE, FALSE);