Forza Horizon 4 and 5 fail to launch due an error with steamclient

[Giovani1906]

Both games fail while using proton-tkg with the following error:

5981.178:013c:0174:err:steamclient:create_win_interface Don't recognize interface name: SteamClient021
5981.178:013c:0174:warn:debugstr:OutputDebugStringA "[S_API] SteamAPI_Init(): No SteamClient021\n"

The issue appeared somewhere after July 17th.
The values set in the config that aren't the same as the repository are:

_LOCAL_PRESET="valve-exp-bleeding"
_wayland_driver="true"
_reuse_built_gst="true"
_build_gstreamer="true"
_lib32_gstreamer="true"

Proton 9.0-2, Proton Experimental, GE-Proton and Proton CachyOS work fine.

Tested on Gentoo and CachyOS.

[Tk-Glitch]

I've been working on fixing this since then. It's linked to some upstream changes in lsteamclient that aren't working with our build system just yet. Once we get this to work we should be all good.