Initialize mutexes and cond variables.

Don't assume that clearing the phread_mutex_t and pthread_cond_t variables
to zero is enough to consider them initialized. Use proper initialization
functions.

git-svn-id: http://streamboard.de.vu/svn/oscam/trunk@8604 4b0bc96b-bc66-0410-9d44-ebda105a78c1