omzmq: add mutex calls for "BIND" case

This makes sure only one action instance is active at any time if we
use BIND mode (where we cannot support multiple instances).

Note that this patch alone is insufficent, as we also need to modify
how the socket is obtained. That's for another patch.
omzmq: make BIND mode work

For this, I added an addtl zocket parameter to pData, which is used
in BIND mode (as it is the sole one!). I don't have a test env, so
there may even be some compile time errors. Also, I may have overlooked
a zocket instance. That means someone else must verify my changes. They
should be good enough though, to get you guys going ;)
omzmq: remove redundant dbgprintf

the error message handler automatically does a dbgprintf
Merge pull request #1 from rgerhards/newzmq-rg

supporting the BIND case