src/libpcp/src/secureserver.c: remove nested locking
src/libpcp/src/secureserver.c: remove nested locking

Uncovered when moving from __pmLock_libpcp (recursive) to
secureserver_lock (not recursive).

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp