tests: Don't define TEST_DRIVER_DIR
tests: Don't define TEST_DRIVER_DIR

It's no longer used anywhere.

Signed-off-by: Andrea Bolognani <3ada0bee826c753786fdbba72243dfba997094cf@redhat.com>
Reviewed-by: Martin Kletzander <e82f23e74d43760279ebcc505dac4ae70d5627d0@redhat.com>

zippy2/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,jardasgit/libvirt,nertpinx/libvirt,olafhering/libvirt,crobinso/libvirt,jardasgit/libvirt,nertpinx/libvirt,jfehlig/libvirt,zippy2/libvirt,eskultety/libvirt,libvirt/libvirt,nertpinx/libvirt,jfehlig/libvirt,eskultety/libvirt,andreabolognani/libvirt,nertpinx/libvirt,libvirt/libvirt,jfehlig/libvirt,crobinso/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,eskultety/libvirt,andreabolognani/libvirt,libvirt/libvirt,olafhering/libvirt,fabianfreyer/libvirt,olafhering/libvirt,libvirt/libvirt,andreabolognani/libvirt,zippy2/libvirt,andreabolognani/libvirt,jardasgit/libvirt,olafhering/libvirt,zippy2/libvirt,crobinso/libvirt,jfehlig/libvirt,eskultety/libvirt,eskultety/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,crobinso/libvirt,fabianfreyer/libvirt