bug#32210: Support medium weighted fonts

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: carlosjosepita@gmail.com,  32210@debbugs.gnu.org
> Date: Wed, 20 Oct 2021 14:58:12 +0200
> 
> /* Table of weight numeric values and their names.  This table must be
>    sorted by numeric values in ascending order.  */
> 
>  static const struct table_entry weight_table[] =
>  {
>    { 0, { "thin" }},
> -  { 20, { "ultra-light", "ultralight" }},
> -  { 40, { "extra-light", "extralight" }},
> -  { 50, { "light" }},
> -  { 75, { "semi-light", "semilight", "demilight", "book" }},
> -  { 100, { "normal", "medium", "regular", "unspecified" }},
> -  { 180, { "semi-bold", "semibold", "demibold", "demi" }},
> -  { 200, { "bold" }},
> -  { 205, { "extra-bold", "extrabold" }},
> -  { 210, { "ultra-bold", "ultrabold", "black" }}
> 
> What are those numbers?  Is it just an ordering, and it doesn't matter
> what the numbers are?  Or are they used when instantiating fonts
> somewhere?

It's used in faces.el.