Log Message:
Update net/openslp to 1.0.10.  Changes from version 1.0.9a include:

* Fixed SA->DA registration logic that excluded some mortal registrations.
* Fixed aging problem that aged out static registrations.
* Fixed SLPDeReg().
* Fixed a segfault generated by a freed but unlinked SLPDSocket.
* Made net.slp.multicastIF actually work.