Currently Ubuntu 25.10 live DVD (ubuntu-25.10-desktop-amd64.iso)
does not include the library, preventing the GUI from being
run. On the other hand, if used unconditionally, it causes
the warning (even in the U25.10) for which it was removed:
<https://github.com/linuxdeploy/linuxdeploy/issues/152>
So preload the library if is in the system and use the bundled just as
a fallback.
The command-line tools used here (eg. stat) may use our custom libraries
(like libselinux) which may not be entirely compatible (it just most
likely ends up with a warning).
+ do the same for get_tools() and set_libva_ld_preload()
+ use original (if any) LD_LIBRARY_PATH for set_ld_preload()
+ removed unneeded `exit $?` (it is implicit)
libpipewire is incompatible with preloaded jack on current Arch and
causes a crash (unsatisfied jack pipewire function dependency).
Anyways, the pipewire screen capture didn't work with the bundled
library, anyways, so we certainly need one from system.
This effectively reverts 3c9b8293.
libjack.so.0 is a dependency also for different modules like portaudio
so if we do not want to depend on instance in the system, we must ship
our version.
