Providing `--dynamic_mode=fully` (for example setting it in
`local.bazelrc`) will now work.
All runfiles are now copied in the extractor pack: in dynamic mode,
those will be the executable and the dynamic libraries, while in static
mode only the executable will be part of the runfiles.
Setting the correct `LD_LIBRARY_PATH` in `qltest.sh` then allows to
run tests with this pakcage. If we need something more, we can switch to
a wrapper script in place of `extractor` in the future.
Notice that `LD_LIBRARY_PATH` is also set in static mode, but that has
no consequence.
