patch 9.0.0670: no space for command line when there is a tabline

Problem:    No space for command line when there is a tabline.
Solution:   Correct computation of where the command line should be.
            (closes #11295)
diff --git a/src/window.c b/src/window.c
index 1f3f9ad..f63b856 100644
--- a/src/window.c
+++ b/src/window.c
@@ -4332,7 +4332,7 @@
     // When cmdheight is changed in a tab page with '<C-w>-', cmdline_row is
     // changed but p_ch and tp_ch_used are not changed. Thus we also need to
     // check cmdline_row.
-    if ((row < cmdline_row) && (cmdline_row <= Rows - p_ch))
+    if (row < cmdline_row && cmdline_row <= Rows - p_ch)
 	clear_cmdline = TRUE;
 
     // The tabpage line may have appeared or disappeared, may need to resize
@@ -6665,7 +6665,7 @@
 	return;
 
     // Update cmdline_row to what it should be: just below the last window.
-    cmdline_row = topframe->fr_height;
+    cmdline_row = topframe->fr_height + tabline_height();
 
     // If cmdline_row is smaller than what it is supposed to be for 'cmdheight'
     // then set old_p_ch to what it would be, so that the windows get resized