How VOID OS 1.0.152 builds its modified Qt Multimedia library (lib/libQt6Multimedia.so.6)

Inputs
  - Qt 6.11.1 prebuilt for Linux desktop gcc_64 (modules: base, qtmultimedia, qtpdf), the same
    runtime VOID ships, from https://download.qt.io/online/qtsdkrepository/linux_x64/desktop/
  - qtshadertools-everywhere-src-6.11.1.tar.xz (build tool for Qt Multimedia)
  - qtmultimedia-everywhere-src-6.11.1.tar.xz
  - qtmultimedia-6.11.1-void-voice-lifetime.patch (the only change)
  Build host: Ubuntu 24.04, gcc/g++ 13, CMake, Ninja, PipeWire and PulseAudio development files.

Steps
  1. Build and install Qt Shader Tools 6.11.1 into a prefix:
       cmake -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo -DQt6_DIR=<qt>/lib/cmake/Qt6 \
             -DCMAKE_INSTALL_PREFIX=<st-inst> <qtshadertools source>
       ninja && ninja install
  2. Unpack Qt Multimedia 6.11.1 and apply the patch:
       patch -p1 < qtmultimedia-6.11.1-void-voice-lifetime.patch
     (qtmultimedia-6.11.1-void-modified-src.tar.xz is this result.)
  3. Configure and build:
       cmake -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo -DBUILD_SHARED_LIBS=ON \
             -DQt6_DIR=<qt>/lib/cmake/Qt6 -DCMAKE_PREFIX_PATH=<st-inst> \
             -DFEATURE_ffmpeg=OFF -DFEATURE_gstreamer=OFF \
             -DFEATURE_pipewire=ON -DFEATURE_pulseaudio=ON \
             -DQT_BUILD_TESTS=OFF -DQT_BUILD_EXAMPLES=OFF <patched qtmultimedia source>
       ninja
  4. Only the resulting libQt6Multimedia.so.6 (debug information split off) replaces Qt's
     file in VOID's runtime/qt/lib. Every other Qt file is the unmodified prebuilt release.

To use your own build: put your libQt6Multimedia.so.6 (same Qt 6.11.1 ABI) in
runtime/qt/lib of the active VOID release. VOID loads it from there; nothing links it statically.