bug#64822: Broken tab-bar rendering when increasing internal-border-width

[Po Lu]

GB <g.bickovich@gmail.com> writes:

> Reproduction steps:
> - emacs -Q
> - Evaluate this expression:
>   (add-to-list 'default-frame-alist '(internal-border-width . 10))
> - Create a new frame (C-x 5 2)
> - Create a new tab (C-x t 2)
> - Wait a second or start typing
>
> Results:
> The tab bar gets cut in half by the area where text is.
> Switching tabs flashes the tab bar the way it's supposed to look like for a 
> split second.
>
> In GNU Emacs 29.0.92 (build 1, x86_64-pc-linux-gnu, GTK+ Version
> 3.24.37, cairo version 1.16.0)
> System Description: Guix System
>
> Configured using:
>  'configure
>  
> CONFIG_SHELL=/gnu/store/rib9g2ig1xf3kclyl076w28parmncg4k-bash-minimal-5.1.16/bin/bash
>  
> SHELL=/gnu/store/rib9g2ig1xf3kclyl076w28parmncg4k-bash-minimal-5.1.16/bin/bash
>  --prefix=/gnu/store/ilmaczmnssmxir9qlqsg6hrp26xa8n5s-emacs-next-pgtk-29.0.92
>  --enable-fast-install --with-pgtk --with-modules --with-cairo

This was fixed on master a month ago, but I didn't judge the fix safe
enough for Emacs 29.  Sorry for that.