Fixed confusion in the configure process:
Removed build of chirp_client.so, which was generally unused and causing build headaches.
external_dynlibs is now simply the set of dlls used by all processes in the build.
abspath goes in configure.tools
Removed unused MPI dependency and code.
Removed unused Kerberos support.
Added the --single-shot option to the worker to cause it to exit quickly
after the master disconnects.  This accelerates the test suite by eliminating
a fair amount of idle waiting.
Eliminate use of kill from test scripts, this has an unavoidable
race condition which can accidentally kill off unrelated processes
when the system is busy.
Modified chirp tests to advertise to localhost, so that the global
catalog is not filled with transient runs.
Dial down the size of the chirp and wq benchmarks, so they finish
in a more reasonable time.
Speed up composite test by running worker in single-shot mode,
and master in work sampling mode. Minutes are reduced to seconds.
Rewrote to avoid using perl Switch module, which may not be universally available.
Again do not use kill here, because pids may have expired and
something else may get killed.
Added timing for each test to see which one is so darn slow.
Pushed combined doit method down into test framework.
Moved control back into run_all_tests, since test scripts sometimes
call exit directly.
Simplified child check logic in work_queue_worker: signal handler
now sets flag so that we can detect signals that happen outside
of link_usleep_mask.
Change allpairs test back to fine granularity, to test WQ small task changes.
No more killing.
Debugging to see why single shot is not taking effect.
Fixed serious bug in gpu detection:

If the script cctools_gpu_autodetect was not found in the path,
an extra forked process would be left hanging around, typically
in work_queue_worker!

Symptoms of this problem include strange behavior after a worker
should have exited, including slow build and test results.
Moved test support scripts from dttools/src to dttools/test.
Removed debugging output.