remove trivial goals from sessions

examples/optimal_replay/why3session.xml

examples/optimal_replay/why3shapes.gz

examples/pairing_heap_bin/why3session.xml

examples/pairing_heap_bin/why3shapes.gz

examples/patience/why3session.xml

examples/patience/why3shapes.gz

examples/prover/BacktrackArray/why3session.xml

examples/prover/BacktrackArray/why3shapes.gz

examples/prover/Firstorder_symbol_spec/why3session.xml

examples/prover/Firstorder_symbol_spec/why3shapes.gz

examples/random_access_list/why3session.xml

examples/random_access_list/why3shapes.gz

examples/register_allocation/why3session.xml

examples/register_allocation/why3shapes.gz

examples/residual/why3session.xml

examples/residual/why3shapes.gz

examples/ropes/why3session.xml

examples/ropes/why3shapes.gz

examples/same_fringe/why3session.xml

examples/same_fringe/why3shapes.gz