vchoi_fork

Add a `skip compact` configuration for skipping the "zoo" tests for
compact datasets.

Bundle the zoo-test configuration into a new type, zoo_config_t.

Add a couple new "zoo" test phases, "delete" and "validate-deletion", to
the existing "create" and "verify" phases.  Give names and numbers to
all phases with the new `enum`, `phase_t`, and refactor so that tend_zoo
runs a selection of phases at each step.

Stub the "delete" and "validate-deletion" phases for most test steps.
Actually implement for compact dataset (ds_cpt_i) test.

In tend_zoo(), delay for 50 milliseconds after running all steps.
Really, this should delay after each step....

Implement vfd_swmr_writer_may_increase_tick_to() and
vfd_swmr_reader_did_increase_tick_to() with a file that reader and
writer share.  The reader saves its current tick number in the shared
file.  The writer does not advance its tick number past the reader's.
Collect some statistics in vfd_swmr_writer_may_increase_tick_to() and
print them before the writer exits.

Add option flags for skipping compact dataset tests (-C) and for
printing error stacks (-e).  Update the usage message, which was
stale before the new options were added.

Delete some dead code.

Add #if 0'd-out code for the reader to wait for the writer before
running "delete" and "validate-deletion" steps.