add back (dummy) libqmapboxgl.so

[adeebshihadeh]

Fixes commaai/openpilot#33811.

The old updater UI binary checked in is unfortunately linked against libqmapboxgl.so even though it doesn't use anything from it. This is fixed with a new updater checked in, but we need to add this dummy version around for one version to maintain backwards compatibility.

echo "void dummy() {}" > dummy.c
gcc -shared -o libqmapboxgl.so -fPIC dummy.c