Implemented '-r' flag to clean up old logs in global_replica_status.sh.
When this flag is used and upon successful completion of the script
with exit code 0, old logs are cleaned up honoring the $KEEPLOGS
setting in /p4/common/bin/p4_vars (as documented in the script).
Also fixed issue where a proper error message was obscured if the
sdp_hosts.cfg file was missing.