(ITS#6132) slapi_entry_has_children broken

[h.b.furuseth@usit.uio.no]

Full_Name: Hallvard B Furuseth
Version: HEAD
OS: 
URL: 
Submission from: (NULL) (129.240.6.233)
Submitted by: hallvard


slapi_entry_has_children() does not check for errors, and also calls
the database's be_has_subordinates handler even when it does not exist.

Finally, when there is no be_has_subordinates to call, it builds
and destroys a pblock which isn't used for anyting.  I don't know
what a pblock is, but it looks like a waste of time.

Fixing.