(un)locking mutex in ctor
(un)locking mutex in ctor

this is a bit of a dummy operation, as it (un)locks the mutex before
the thread is even created.
it's mainly here to satisfy coverity.

CID:22423
CID:22424
CID:22425

umlaeute/ambix,umlaeute/ambix,iem-projects/ambix,umlaeute/ambix,kronihias/libambix,iem-projects/ambix,iem-projects/ambix,kronihias/libambix