Ensure thread safety for Globus and OpenSSL in cream_gahp. #4406

Since we're creating multiple worker threads in the cream_gahp, we need
to call certain initialization functions for Globus and gsoap in the
main thread before any new threads are created. Otherwise, OpenSSL and
Globus functions/data are accessed in a non-thread-safe way.
When under load, this results in frequent crashes.
Make number of cream_gahp worker threads configurable. #4406

CREAM_GAHP_WORKER_THREADS can be set in the config file or the
environment to set the number of worker threads created by the
cream_gahp. The default remains 6, as before.
Version history for cream_gahp crash fix. #4406