patch 8.2.1401: cannot jump to the last used tabpage

Problem:    Cannot jump to the last used tabpage.
Solution:   Add g<Tab> and tabpagnr('#'). (Yegappan Lakshmanan, closes #6661,
            neovim #11626)
diff --git a/src/evalwindow.c b/src/evalwindow.c
index 0b3052c..b50776d 100644
--- a/src/evalwindow.c
+++ b/src/evalwindow.c
@@ -616,6 +616,9 @@
 	{
 	    if (STRCMP(arg, "$") == 0)
 		nr = tabpage_index(NULL) - 1;
+	    else if (STRCMP(arg, "#") == 0)
+		nr = valid_tabpage(lastused_tabpage) ?
+					tabpage_index(lastused_tabpage) : 0;
 	    else
 		semsg(_(e_invexpr2), arg);
 	}