[heavy] adding dev libraries to build SDL3
Valve would like to build SDL3 in steamrt-heavy as part of the steamwebhelper build.
We've already updated the rest of the Steam client build, SDL3 is now built inline in steamrt-scout with the rest of the client. That has made iteration and bug fixing easier. But heavy is missing a number of packages in order to catchup.
This is the list of -dev dependencies (taken from the SDL3 build scripts):
libasound2-dev libpulse-dev libaudio-dev libjack-dev libsndio-dev libsamplerate0-dev libx11-dev libxext-dev libxrandr-dev libxcursor-dev libxfixes-dev libxi-dev libxss-dev libxkbcommon-dev libdrm-dev libgbm-dev libgl1-mesa-dev libgles2-mesa-dev libegl1-mesa-dev libdbus-1-dev libibus-1.0-dev libudev-dev fcitx-libs-dev libpipewire-0.3-dev libwayland-dev libdecor-0-dev
Some of these may already be present obviously. A quick check on our end suggests all these packages already exist, except for libpipewire-dev.
There may also be several libraries that will need to make their way into the runtime?