New make target check

New make target check

Just a smoke test so far, extracted from src/scripts/nightly/.  This
makes the existing smoke test more easily accessible.  Noteworthy
differences:

* Instead of patching the code to make output more stable, postprocess
  the output to normalize it.

* Compare actual results to expected results instead of the previous
  test run's results.

* Much faster.  The old test harness used sleep liberally to "ensure"
  things always happen in the same order.

Known shortcomings:

* The smoke test hangs when the server fails to complete startup, or
  fails to terminate.

* Normalization of xdump hardcodes columns instead of getting them
  from xdump meta.

* Normalization of time values in xdump is an ugly hack.

* xdump meta column type isn't normalized.  Actual values can vary
  between systems, because the width of enumeration types is
  implementation-defined.  The smoke test works only when they're
  represented as int, which is the case on common systems.

* Currently expected to work only with thread package LWP and a
  random() that behaves exactly like the one on my development system,
  because:

  - Thread scheduling is reliably deterministic only with LWP

  - The PRN sequence produced by random() isn't portable

  - Shell builtin kill appears not to do the job in MinGW

  - The Windows server tries to run as service when -d isn't
    specified

Further work is needed to address these shortcomings.

Getting C programs behave exactly the same on all systems is hard.
We'll likely run into system-dependent differences that upset the
smoke test.  Floating-point computation seems particularly vulnerable.

Instead of updating src/scripts/nightly/ to use "make check", retire
it.  It hasn't been used in quite a while.  Investing more into our
homegrown auto-builder doesn't make sense, as canned auto-builders
such as Travis CI and Jenkins are readily available.

The shell scripts src/scripts/nightly/tests/?? become Empire batch
files tests/smoke/.  The shell scripts are actually shell boilerplate
around Empire batch files.  To make sure git recognizes the move, this
commit moves them unchanged.  tests/smoke-test strips the boilerplate
before it feeds the batch files to the client.  The next commit will
get rid fo that.