multimedia/qt6-multimedia: Fix 32-bit builds

/wrkdirs/usr/ports/multimedia/qt6-multimedia/work/qtmultimedia-everywhere-src-6.8.3/src/multimedia/pulseaudio/qpulseaudiosink.cpp:499:89:
error: non-constant-expression cannot be narrowed from type 'qint64' (aka 'long long') to 'qsizetype' (aka 'int') in initializer list [-Wc++11-narrowing]

499 |                                       QSpan{ reinterpret_cast<const std::byte *>(data), len },
    |                                                                                         ^~~

/wrkdirs/usr/ports/multimedia/qt6-multimedia/work/qtmultimedia-everywhere-src-6.8.3/src/multimedia/pulseaudio/qpulseaudiosink.cpp:499:89:
note: insert an explicit cast to silence this issue

499 |                                       QSpan{ reinterpret_cast<const std::byte *>(data), len },
    |                                                                                         ^~~
    |                                                                                         static_cast<qsizetype>( )

/wrkdirs/usr/ports/multimedia/qt6-multimedia/work/qtmultimedia-everywhere-src-6.8.3/src/multimedia/pulseaudio/qpulseaudiosink.cpp:500:83:
error: non-constant-expression cannot be narrowed from type 'qint64' (aka 'long long') to 'qsizetype' (aka 'int') in initializer list [-Wc++11-narrowing]

500 |                                       QSpan{ reinterpret_cast<std::byte *>(dest), len });
    |                                                                                   ^~~

/wrkdirs/usr/ports/multimedia/qt6-multimedia/work/qtmultimedia-everywhere-src-6.8.3/src/multimedia/pulseaudio/qpulseaudiosink.cpp:500:83:
note: insert an explicit cast to silence this issue

500 |                                       QSpan{ reinterpret_cast<std::byte *>(dest), len });
    |                                                                                   ^~~
    |                                                                                   static_cast<qsizetype>( )

2 errors generated.

Reported by: pkg-fallout